The 59-row fixture is windowed on current main
2026-09-30 · Bug · Medium priority · Medium effort
NOT REPRODUCED in the tested current-main synthetic scenario. High confidence in the functional threshold result; limited confidence in generalizing timings to the original thread. The remaining real-thread latency claim is unresolved.
Tested claim and result
The issue combines a former 60-row desktop threshold with lag in a rich thread, including lag after windowing starts. This experiment mounts the actual ThreadTimelineRows renderer in an optimized browser fixture. Both clean runs show no virtual spacer at 2 or 19 rows and bounded mounting with a virtual spacer at 20 and 59 rows. The 59-row desktop and compact captures each initially mount 10 rows, containing 1,270 timeline descendant elements and 320 rendered synthetic command-output lines. It does not mount all 59 rows.
The current threshold behavior is directly verified, rather than inferred from a merged PR. The source change removing the old top-level overrides is present in the tested base. No old-revision timing run was performed. The browser fixture did not reproduce scroll long tasks, but it cannot establish that the broader reported latency is fixed. No issue closure or whole-issue ALREADY FIXED claim is made.
Dataset and meaningful limits
At 59 input rows, the fixture alternates 30 assistant Markdown messages and 29 command-work rows. Each message contains eight sections with headings, formatted paragraphs, a two-row table and a two-item list. Each command row has 80 lines of synthetic output and is initially expanded. Smaller datasets use the same row generator, truncated to 2, 19 or 20 rows. Command text is display data only and is never executed.
This is an actual component render with the production React compiler, app CSS, font assets, routing/query providers and a controlled scroll context. It is not a complete bb app, live provider, server timeline build, 20-segment fetch/pagination, original 0.44.0 desktop package or reconstruction of the reporter’s private content. It has no iframes, images, streaming updates or real user data. Its 1,270-node initial 59-row DOM is a different workload from the original reported 6,616-node unwindowed DOM. The supplied bottom-anchor actions are no-ops; real bottom anchoring, search/navigation and history loading are not tested.
Trusted base and environment
Fetched public origin/main: 2ffb754e7bc83d29607e6279a07eb1530a0e6cd6. Linux x86_64, Node 24.19.0, pinned pnpm 9.15.0, Vite 8.0.12 production build and headless desktop Chromium 151.0.7922.173. Desktop viewport 1100×800 CSS pixels; the compact functional control uses a 600×800 desktop viewport with the compact override, not an actual mobile browser. Scroll container client height is 568 pixels.
Two clean checkouts at the identical SHA, separate node_modules/caches, separate browser profiles and loopback server/debugger ports. Dependency downloads are shared. The optimized fixture uses the repository shared Vite configuration, excluding only the full-shell font-preload and split-prefetch HTML hooks. An initial first-checkout build stopped because its standalone HTML lacked the full-shell theme-script marker; those shell-only hooks were removed from the fixture config before both successful measured builds. No production code was changed and no dependency was added.
Measurement method
Per checkout: four dataset sizes × three fresh-document samples plus three warm-scroll samples = 24 samples, with 30 scroll steps each (720 steps). Across both checkouts: 48 samples and 1,440 steps. Fresh-document means navigation with HTTP cache disabled and a fresh React mount in the existing browser process; it is not cold OS/process/cache startup. Warm-scroll means three further sweeps of the same mounted component. The first browser had a visual setup probe before measurement. Neither run uses CPU throttling or a dedicated performance machine.
Mount time runs from the synthetic mount-button click to the third animation frame. After a 350 ms settling interval, the script records DOM/windowing state. A scroll sweep resets to the top, waits 150 ms, then advances through 30 fractions of the current scroll extent; each step waits three animation frames. Long Tasks API entries overlapping the sweep are counted. The roughly 50 ms step baseline is deliberately imposed by that three-frame wait; it is not event-handler CPU time, input latency, a frame-rate claim or directly comparable to the issue’s 215 ms per-step statistic. Mount timing is separate from scroll long-task collection. No server latency is measured.
Observed summaries
| Run | Rows | Condition | Step p95 / max (ms) | Long tasks | Three mount samples (ms) |
|---|---|---|---|---|---|
| first | 2 | cold-document | 50.2 / 50.4 | 0 | 66.5, 53.6, 63.3 |
| first | 2 | warm-scroll | 50.2 / 53.1 | 0 | — |
| first | 19 | cold-document | 50.2 / 50.7 | 0 | 175.1, 202.7, 187.5 |
| first | 19 | warm-scroll | 50.2 / 52.1 | 0 | — |
| first | 20 | cold-document | 50.2 / 50.4 | 0 | 169.2, 184.3, 128.5 |
| first | 20 | warm-scroll | 50.3 / 50.4 | 0 | — |
| first | 59 | cold-document | 50.7 / 58.5 | 0 | 164.3, 216.3, 195.5 |
| first | 59 | warm-scroll | 50.2 / 50.6 | 0 | — |
| second | 2 | cold-document | 50.2 / 50.7 | 0 | 95.3, 52.9, 40.1 |
| second | 2 | warm-scroll | 50.1 / 50.6 | 0 | — |
| second | 19 | cold-document | 50.2 / 50.4 | 0 | 198.1, 189.3, 183.2 |
| second | 19 | warm-scroll | 50.2 / 51.1 | 0 | — |
| second | 20 | cold-document | 50.2 / 50.9 | 0 | 154.7, 132.1, 172.4 |
| second | 20 | warm-scroll | 50.3 / 50.5 | 0 | — |
| second | 59 | cold-document | 50.6 / 52.0 | 0 | 156.0, 200.3, 140.2 |
| second | 59 | warm-scroll | 50.3 / 50.5 | 0 | — |
Each p95 is the sorted value at floor(0.95 × (n−1)) from 90 step measurements. Both runs recorded zero scroll long tasks for all datasets. The three timed 59-row mounts ranged from 164.3–216.3 ms in the first run and 140.2–200.3 ms in the second. Separate screenshot-only mounts are present in the raw evidence and excluded from these repeated-sample summaries. Mounting is not free; the absence of scroll long tasks does not establish a universally fast timeline.
Exact repeatable steps
git clone https://github.com/get-bb/bb.git bb-repro cd bb-repro git checkout --detach 2ffb754e7bc83d29607e6279a07eb1530a0e6cd6 corepack pnpm install --frozen-lockfile # Save the three fixture files below under apps/app/issue4445/. cd apps/app corepack pnpm exec vite build --config issue4445/vite.config.ts python -m http.server 49201 --bind 127.0.0.1 --directory issue4445/dist
In separate terminals, start a disposable browser and run the inline measurement script saved outside the reports repository:
chromium --headless --no-sandbox --disable-dev-shm-usage --disable-background-networking --no-first-run --remote-debugging-address=127.0.0.1 --remote-debugging-port=49202 --user-data-dir="$(mktemp -d)" about:blank node measure.mjs 49202 49201 first-run
Repeat personally in a second clean checkout at the identical SHA with separate dependencies, profile and data. Use HTTP/debugger ports 49203/49204:
node measure.mjs 49204 49203 second-run
Both frozen installs, optimized builds and measurement scripts must complete successfully. Use pnpm 9.15.0 for subprocesses too. This environment used task-local Corepack and writable caches. The script asserts actual windowing and tool-output presence. Stop the disposable servers/browsers when done; all owned processes were stopped after this investigation.
apps/app/issue4445/index.html
<!doctype html><html><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>4445 synthetic rich timeline</title></head><body><div id="root"></div><script type="module" src="/main.tsx"></script></body></html>
apps/app/issue4445/vite.config.ts
import { defineConfig } from "vite";
import { sharedViteConfig } from "../vite.config";
export default defineConfig({ ...sharedViteConfig, root: __dirname, plugins: sharedViteConfig.plugins.filter(plugin => !["bb:font-preload", "bb:split-prefetch"].includes(plugin.name)), build: { ...sharedViteConfig.build, outDir: "dist", emptyOutDir: true } });
apps/app/issue4445/main.tsx
import { useMemo, useRef, useState } from "react";
import { createRoot } from "react-dom/client";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
import { MemoryRouter } from "react-router-dom";
import { CompactViewportOverrideProvider } from "@bb/shared-ui/hooks/use-compact-viewport";
import { ThreadTimelineRows } from "../src/components/thread/timeline/ThreadTimelineRows";
import { BottomAnchorContext } from "../src/components/ui/bottom-anchored-scroll-body";
import { conversationRow, commandRow } from "../src/test/fixtures/thread-timeline-rows";
import "../src/app.css";
const params = new URLSearchParams(location.search);
const count = Number(params.get("rows") ?? 59);
const compact = params.get("compact") === "1";
const paragraph = "Synthetic detailed result with **bold text**, *emphasis*, and `inline code`. No real thread data is used.";
const markdown = Array.from({ length: 8 }, (_, i) => `### Synthetic section ${i}\n\n${paragraph}\n\n| Field | Value |\n| --- | --- |\n| Color | Blue |\n| Status | Ready |\n\n- First synthetic observation\n- Second synthetic observation\n`).join("\n");
const rows = Array.from({ length: count }, (_, i) => i % 2 === 0
? conversationRow({ id: `fixture-message-${i}`, seq: i + 1, role: "assistant", text: `Synthetic row ${i}\n\n${markdown}`, turnId: `synthetic-turn-${i}`, threadId: "thr_synthetic" })
: commandRow({ id: `fixture-command-${i}`, seq: i + 1, command: "synthetic display-only command", cwd: "/synthetic/project", output: Array.from({ length: 80 }, (_, n) => `Synthetic output line ${n}: result ready`).join("\n"), turnId: `synthetic-turn-${i}`, threadId: "thr_synthetic" }));
const query = new QueryClient({ defaultOptions: { queries: { retry: false } } });
function Timeline() {
const scroll = useRef<HTMLDivElement>(null);
const anchor = useMemo(() => ({ captureScrollAnchor: () => () => {}, getScrollElement: () => scroll.current, isAtBottom: false,
scrollElementIntoView: () => {}, scrollElementIntoViewClampedToMaxScroll: () => {}, scrollToBottom: () => {} }), []);
return <div id="scroll" ref={scroll} style={{ height: 570, overflow: "auto", border: "1px solid #777", position: "relative" }}>
<BottomAnchorContext.Provider value={anchor}><CompactViewportOverrideProvider isCompactViewport={compact}>
<ThreadTimelineRows timelineRows={rows} initialExpanded={new Set(rows.filter(r => r.kind === "work").map(r => r.id))}
threadRuntimeDisplayStatus="idle" workspaceRootPath={undefined} />
</CompactViewportOverrideProvider></BottomAnchorContext.Provider>
</div>;
}
function App() {
const [mounted,setMounted]=useState(false);
return <main style={{ margin: "18px auto", maxWidth: 950, padding: 12 }}>
<h1 style={{ fontSize: 24 }}>Isolated rich timeline — {count} top-level input rows</h1>
<p>{Math.ceil(count/2)} Markdown messages; {Math.floor(count/2)} expanded command outputs. Synthetic fixture, not a full app session.</p>
<button id="mount" onClick={() => setMounted(true)}>Mount timeline</button>
<span id="state">{mounted ? "mounted" : "ready"}</span>
{mounted ? <Timeline /> : null}
</main>;
}
createRoot(document.getElementById("root")!).render(<MemoryRouter><QueryClientProvider client={query}><App /></QueryClientProvider></MemoryRouter>);
measure.mjs
import { writeFile } from 'node:fs/promises';
const [debugPort,appPort,output]=process.argv.slice(2);
const tabs=await(await fetch(`http://127.0.0.1:${debugPort}/json/list`)).json();
const ws=new WebSocket(tabs.find(t=>t.type==='page').webSocketDebuggerUrl);
await new Promise(r=>ws.addEventListener('open',r,{once:true}));let id=0;const pending=new Map();
ws.addEventListener('message',event=>{const x=JSON.parse(event.data);if(x.id){const p=pending.get(x.id);pending.delete(x.id);x.error?p.reject(new Error(JSON.stringify(x.error))):p.resolve(x.result);}});
const call=(method,params={})=>new Promise((resolve,reject)=>{const serial=++id;pending.set(serial,{resolve,reject});ws.send(JSON.stringify({id:serial,method,params}));});
const evaluate=async expression=>{const x=await call('Runtime.evaluate',{expression,returnByValue:true,awaitPromise:true});if(x.exceptionDetails)throw new Error(JSON.stringify(x.exceptionDetails));return x.result.value;};
await call('Page.enable');await call('Runtime.enable');await call('Network.enable');await call('Network.setCacheDisabled',{cacheDisabled:true});
await call('Emulation.setDeviceMetricsOverride',{width:1100,height:800,deviceScaleFactor:1,mobile:false});
const errors=[];
ws.addEventListener('message',event=>{const x=JSON.parse(event.data);if(x.method==='Runtime.exceptionThrown')errors.push(x.params.exceptionDetails.text+': '+(x.params.exceptionDetails.exception?.description??''));});
const pause=ms=>new Promise(r=>setTimeout(r,ms));
async function load(rows,compact=false){
await call('Page.navigate',{url:`http://127.0.0.1:${appPort}/?rows=${rows}&compact=${compact?1:0}`});
for(let n=0;n<200;n++){if(await evaluate('document.getElementById("state")?.textContent === "ready"'))return;await pause(30);}throw new Error('Fixture load timeout');
}
const snapshot=()=>evaluate(`(()=>{const s=document.getElementById('scroll');return {mountedRows:s.querySelectorAll('[data-timeline-row-id]').length,spacers:s.querySelectorAll('[data-timeline-virtual-spacer]').length,domNodes:s.querySelectorAll('*').length,scrollHeight:s.scrollHeight,clientHeight:s.clientHeight,commandOutputLines:(s.textContent.match(/Synthetic output line/g)||[]).length,windowPosition:getComputedStyle(s.querySelector('[data-timeline-window-key]')).position};})()`);
async function mount(){const result=await evaluate(`(async()=>{const start=performance.now();document.getElementById('mount').click();await new Promise(r=>requestAnimationFrame(()=>requestAnimationFrame(()=>requestAnimationFrame(r))));return {mountToThirdFrameMs:performance.now()-start};})()`);await pause(350);return {...result,...await snapshot()};}
async function scroll(){return await evaluate(`(async()=>{const s=document.getElementById('scroll');s.scrollTop=0;await new Promise(r=>setTimeout(r,150));const tasks=[];const observer=new PerformanceObserver(list=>tasks.push(...list.getEntries().map(e=>({start:e.startTime,duration:e.duration}))));observer.observe({type:'longtask'});const start=performance.now();const steps=[];for(let n=1;n<=30;n++){const a=performance.now();s.scrollTop=(s.scrollHeight-s.clientHeight)*n/30;await new Promise(r=>requestAnimationFrame(()=>requestAnimationFrame(()=>requestAnimationFrame(r))));steps.push(performance.now()-a);}const end=performance.now();await new Promise(r=>setTimeout(r,120));observer.disconnect();return {stepsMs:steps,longTasks:tasks.filter(t=>t.start<end&&t.start+t.duration>start),mountedRows:s.querySelectorAll('[data-timeline-row-id]').length,domNodes:s.querySelectorAll('*').length};})()`);}
const samples=[];
for(const rows of [2,19,20,59]){
for(let repeat=0;repeat<3;repeat++){
await load(rows);const mounted=await mount();
if(rows<20&&mounted.spacers!==0)throw new Error('Unexpected low-count windowing');
if(rows>=20&&(mounted.spacers===0||mounted.mountedRows>=rows))throw new Error('Windowing did not bound mounted rows');
if(mounted.commandOutputLines===0)throw new Error('Expanded tool output missing');
samples.push({rows,condition:'cold-document',repeat,mount:mounted,scroll:await scroll()});
}
for(let repeat=0;repeat<3;repeat++)samples.push({rows,condition:'warm-scroll',repeat,scroll:await scroll()});
}
await load(59);const screenshotState=await mount();
const screenshot=await call('Page.captureScreenshot',{format:'png',captureBeyondViewport:false});await writeFile(output+'.png',Buffer.from(screenshot.data,'base64'));
await call('Emulation.setDeviceMetricsOverride',{width:600,height:800,deviceScaleFactor:1,mobile:false});await load(59,true);const compact=await mount();if(compact.spacers===0||compact.mountedRows>=59)throw new Error('Compact windowing failed');
const compactScreenshot=await call('Page.captureScreenshot',{format:'png',captureBeyondViewport:false});await writeFile(output+'-compact.png',Buffer.from(compactScreenshot.data,'base64'));
if(errors.length)throw new Error(JSON.stringify(errors));
const result={browser:await call('Browser.getVersion'),viewport:{width:1100,height:800},samples,screenshotState,compact,errors};await writeFile(output+'.json',JSON.stringify(result,null,2));console.log(JSON.stringify({samples:samples.length,screenshotState,compact}));ws.close();
Both-run evidence and real screenshots
The same agent personally repeated the experiment in the second clean checkout; this is not independent verification. Timings differ, while threshold behavior is consistent. Browser exceptions were absent in both captures. Screenshots were genuinely captured from each browser; corresponding first/second images happen to be byte-identical because the fixture and view are deterministic. Their image contents and privacy were checked.
First clean checkout
{
"browser": {
"protocolVersion": "1.3",
"product": "Chrome/151.0.7922.173",
"revision": "@a96602f30358e9b5d256a0464e7e4d4bec223004",
"userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36",
"jsVersion": "15.1.206.23"
},
"viewport": {
"width": 1100,
"height": 800
},
"samples": [
{
"rows": 2,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 66.5,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2143,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
47.29999999888241,
49.5,
50.20000000111759,
49.899999998509884,
49.79999999888241,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50,
49.90000000037253,
50.09999999962747,
50,
50,
50,
50,
50,
50,
50,
50,
50,
50.09999999962747
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 53.600000001490116,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2143,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
19.699999999254942,
50,
50,
50,
49.90000000037253,
49.90000000037253,
50.399999998509884,
49.600000001490116,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50,
50,
50,
49.90000000037253,
50.19999999925494,
49.80000000074506,
50,
50.19999999925494,
49.90000000037253,
50,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 63.30000000074506,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2155,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
41.399999998509884,
50.100000001490116,
50,
49.899999998509884,
50.20000000111759,
49.90000000037253,
50.09999999962747,
50.09999999962747,
49.80000000074506,
50,
49.899999998509884,
50.100000001490116,
50.09999999962747,
49.69999999925494,
50.100000001490116,
49.899999998509884,
50.20000000111759,
49.90000000037253,
50.19999999925494,
49.80000000074506,
49.899999998509884,
50,
50.100000001490116,
49.899999998509884,
50,
50,
49.90000000037253,
50.09999999962747,
50,
49.899999998509884
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.699999999254942,
50.100000001490116,
50.5,
49.59999999962747,
50.09999999962747,
49.69999999925494,
50.20000000111759,
49.79999999888241,
50.19999999925494,
49.80000000074506,
50.09999999962747,
50.19999999925494,
49.59999999962747,
50,
50,
50.09999999962747,
49.79999999888241,
50.100000001490116,
50,
49.79999999888241,
53.100000001490116,
47,
49.899999998509884,
50,
50.100000001490116,
49.899999998509884,
50,
50,
50,
51.40000000037253
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
26.299999998882413,
49.90000000037253,
50,
50.09999999962747,
50.100000001490116,
49.79999999888241,
50.09999999962747,
49.80000000074506,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50,
50,
49.90000000037253,
50,
50.09999999962747,
50,
50,
49.90000000037253,
50,
50,
50,
50,
50,
50.09999999962747,
50,
49.90000000037253,
50.40000000037253,
49.69999999925494
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.699999999254942,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50.09999999962747,
50.09999999962747,
49.90000000037253,
50,
50,
50,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
50,
49.90000000037253,
50.09999999962747,
50,
50.09999999962747,
49.90000000037253,
50,
49.90000000037253,
50.09999999962747
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 175.09999999962747,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21327,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
25.59999999962747,
50.09999999962747,
50.20000000111759,
49.69999999925494,
50.70000000111759,
49.29999999888241,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50,
50,
50,
50,
50,
50,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.19999999925494,
50.20000000111759
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 202.7000000011176,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21320,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
29,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
50,
50,
49.90000000037253,
50.09999999962747,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50,
50,
49.90000000037253,
50.19999999925494,
50,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50,
50.30000000074506,
49.69999999925494,
50,
50.19999999925494,
49.80000000074506,
50,
50,
50,
49.90000000037253
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 187.5,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21306,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
34,
50,
49.69999999925494,
50,
50,
50,
50,
50.100000001490116,
49.899999998509884,
50.30000000074506,
49.69999999925494,
50.100000001490116,
49.899999998509884,
50.30000000074506,
49.69999999925494,
50.100000001490116,
49.899999998509884,
50.100000001490116,
50,
49.899999998509884,
50.100000001490116,
50.399999998509884,
49.5,
50.100000001490116,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.699999999254942,
50,
50,
50,
50,
50.100000001490116,
50.19999999925494,
49.69999999925494,
50,
50.100000001490116,
50,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50,
50,
49.899999998509884,
50.100000001490116,
49.899999998509884,
50.100000001490116,
49.899999998509884,
50,
50.100000001490116,
50,
49.899999998509884,
50.20000000111759,
49.79999999888241,
50,
49.90000000037253
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
27.800000000745058,
49.79999999888241,
49.90000000037253,
51.59999999962747,
48.40000000037253,
50.09999999962747,
50,
49.80000000074506,
50.19999999925494,
49.90000000037253,
50.09999999962747,
50.30000000074506,
49.69999999925494,
49.90000000037253,
50.20000000111759,
49.79999999888241,
50,
50.20000000111759,
49.899999998509884,
49.90000000037253,
50.09999999962747,
50,
50,
50,
49.90000000037253,
50,
50,
50,
50,
50
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.5,
50,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50.19999999925494,
49.90000000037253,
50,
50,
49.90000000037253,
50.19999999925494,
50,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50,
50.30000000074506,
49.79999999888241,
49.90000000037253,
50,
50.19999999925494,
49.90000000037253,
50,
50,
49.90000000037253,
50.19999999925494,
49.80000000074506,
50.09999999962747,
49.90000000037253,
52.09999999962747
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 169.2000000011176,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
46.79999999888241,
50.20000000111759,
50.09999999962747,
49.80000000074506,
50,
50.399999998509884,
49.600000001490116,
50.09999999962747,
49.79999999888241,
50,
50,
50,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.80000000074506,
50.09999999962747,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50.09999999962747,
50.40000000037253,
49.59999999962747,
50
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 184.30000000074506,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
37.40000000037253,
50,
50,
50,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50.19999999925494,
49.90000000037253,
50,
50,
49.90000000037253,
50,
50.19999999925494,
50.100000001490116,
49.79999999888241,
50,
50,
50,
49.90000000037253,
49.90000000037253,
50.19999999925494,
50,
49.80000000074506,
50,
50,
50
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 128.5,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
36.90000000037253,
50,
50,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.30000000074506,
49.69999999925494,
49.90000000037253,
50.19999999925494,
50,
50.20000000111759,
49.79999999888241,
50.20000000111759,
49.90000000037253,
49.79999999888241,
50.09999999962747,
50,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50,
50,
50.09999999962747,
50,
50.09999999962747,
50.40000000037253,
49.5,
49.90000000037253,
50.09999999962747
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
26.09999999962747,
50,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50.19999999925494,
49.70000000111759,
50.19999999925494,
49.90000000037253,
50.09999999962747,
50.30000000074506,
50.09999999962747,
49.59999999962747,
49.90000000037253,
50,
50.09999999962747,
50.20000000111759,
49.69999999925494,
50.30000000074506,
49.79999999888241,
50.09999999962747,
50,
49.899999998509884,
49.80000000074506,
50.19999999925494,
49.90000000037253,
50,
49.90000000037253,
49.90000000037253
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
27.40000000037253,
50,
49.90000000037253,
50,
50.19999999925494,
49.70000000111759,
50.09999999962747,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
49.80000000074506,
50,
50.19999999925494,
49.80000000074506,
50.09999999962747,
50.29999999888241,
49.600000001490116,
50.09999999962747,
49.90000000037253,
50.19999999925494,
50.09999999962747,
49.70000000111759,
50.09999999962747,
50.09999999962747,
50.40000000037253,
49.59999999962747,
49.80000000074506,
50,
50
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.90000000037253,
50.20000000111759,
49.5,
50,
50.09999999962747,
50,
50,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50,
50,
50,
49.90000000037253,
50.19999999925494,
49.90000000037253,
50.09999999962747,
50.30000000074506,
49.59999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50.29999999888241,
49.70000000111759,
50.09999999962747
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 164.30000000074506,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27511,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
39.80000000074506,
50.19999999925494,
49.90000000037253,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50.29999999888241,
49.59999999962747,
50.30000000074506,
49.90000000037253,
50.19999999925494,
50.09999999962747,
49.70000000111759,
50.09999999962747,
49.69999999925494,
50.09999999962747,
50,
50.69999999925494,
49.5,
49.59999999962747,
50.100000001490116,
50,
50,
54.399999998509884,
45.600000001490116,
50,
50.5,
49.69999999925494,
49.69999999925494,
50
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 216.30000000074506,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27536,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
26.5,
49.80000000074506,
49.899999998509884,
50,
50,
50.100000001490116,
49.90000000037253,
49.899999998509884,
50,
50,
50.100000001490116,
50,
49.899999998509884,
50.100000001490116,
50,
49.899999998509884,
50.100000001490116,
50,
50,
50,
51.29999999888241,
48.59999999962747,
50.100000001490116,
49.899999998509884,
50.100000001490116,
50.399999998509884,
49.70000000111759,
49.90000000037253,
49.899999998509884,
49.90000000037253
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 195.5,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27549,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
28.699999999254942,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50.40000000037253,
49.69999999925494,
50.19999999925494,
49.80000000074506,
50,
50,
50.69999999925494,
49.40000000037253,
50.20000000111759,
50,
50,
50,
49.79999999888241,
49.90000000037253,
50.09999999962747,
49.80000000074506,
50,
50.90000000037253,
49.09999999962747,
50,
50,
49.90000000037253,
58.5,
41.69999999925494,
49.90000000037253,
49.90000000037253
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.90000000037253,
50,
49.899999998509884,
50.100000001490116,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.19999999925494,
49.80000000074506,
50,
50,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50,
49.899999998509884,
50.09999999962747,
49.90000000037253,
50,
50,
50,
49.899999998509884,
50.09999999962747,
50,
49.90000000037253
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
28.700000001117587,
49.40000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
50.09999999962747,
49.80000000074506,
49.90000000037253,
50,
49.899999998509884,
50.100000001490116,
50,
50,
49.899999998509884,
50,
49.899999998509884,
50,
50.100000001490116,
50.29999999888241,
50.59999999962747,
49.30000000074506,
49.69999999925494,
50.100000001490116,
49.899999998509884,
50.20000000111759,
49.79999999888241,
50,
49.90000000037253
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
28,
50.100000001490116,
49.899999998509884,
50,
50,
50.20000000111759,
49.79999999888241,
50,
50,
49.90000000037253,
50.09999999962747,
50,
50.100000001490116,
49.79999999888241,
50,
50.20000000111759,
49.79999999888241,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.20000000111759,
49.899999998509884,
50,
50.100000001490116,
50.29999999888241,
49.5,
50.20000000111759,
49.899999998509884,
50
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
}
],
"screenshotState": {
"mountToThirdFrameMs": 267.30000000074506,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27558,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"compact": {
"mountToThirdFrameMs": 146.2999999988824,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 28719,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"errors": []
}
First run: desktop.
First run: compact desktop viewport.
Second clean checkout
{
"browser": {
"protocolVersion": "1.3",
"product": "Chrome/151.0.7922.173",
"revision": "@a96602f30358e9b5d256a0464e7e4d4bec223004",
"userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36",
"jsVersion": "15.1.206.23"
},
"viewport": {
"width": 1100,
"height": 800
},
"samples": [
{
"rows": 2,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 95.30000000074506,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2161,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
29,
50,
49.899999998509884,
50.5,
49.600000001490116,
49.79999999888241,
50.09999999962747,
50,
50,
50,
50,
50.100000001490116,
49.79999999888241,
50,
49.90000000037253,
50,
49.90000000037253,
50.09999999962747,
50,
50.20000000111759,
49.79999999888241,
49.90000000037253,
50.20000000111759,
49.899999998509884,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
50.09999999962747
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 52.90000000037253,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2143,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
22.800000000745058,
49.90000000037253,
50.19999999925494,
49.90000000037253,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50.09999999962747,
50.69999999925494,
49.30000000074506,
50,
50,
49.90000000037253,
50,
50.09999999962747,
50,
50.29999999888241,
49.600000001490116,
50.09999999962747,
50,
50.19999999925494,
49.90000000037253,
50,
50
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 40.09999999962747,
"mountedRows": 2,
"spacers": 0,
"domNodes": 224,
"scrollHeight": 2121,
"clientHeight": 568,
"commandOutputLines": 80,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
43.80000000074506,
50.19999999925494,
50,
49.90000000037253,
49.70000000111759,
50.09999999962747,
50,
50,
50,
50.09999999962747,
49.90000000037253,
50,
50,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
50,
50.09999999962747,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50.09999999962747
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.800000000745058,
49.90000000037253,
50,
50,
50,
49.90000000037253,
50,
50.09999999962747,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
49.90000000037253,
50.09999999962747,
50.09999999962747,
50.19999999925494,
49.70000000111759,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50,
50,
50,
50,
50,
50.09999999962747
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
27.699999999254942,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50,
50,
49.90000000037253,
50.29999999888241,
49.70000000111759,
50.09999999962747,
50,
50,
50,
50,
50.09999999962747,
49.80000000074506,
50.09999999962747,
50,
50,
50,
49.90000000037253
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 2,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
28.199999999254942,
49.90000000037253,
49.90000000037253,
50,
50,
50,
50,
50,
50,
49.899999998509884,
50.100000001490116,
50,
50,
50,
50,
50,
50,
50.59999999962747,
49.40000000037253,
50,
49.899999998509884,
50,
50.20000000111759,
50,
49.79999999888241,
50.100000001490116,
49.899999998509884,
50.20000000111759,
49.90000000037253,
49.899999998509884
],
"longTasks": [],
"mountedRows": 2,
"domNodes": 224
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 198.09999999962747,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21327,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
33,
50,
49.899999998509884,
50,
50.30000000074506,
49.80000000074506,
49.899999998509884,
50.100000001490116,
49.69999999925494,
50.100000001490116,
49.899999998509884,
50.100000001490116,
50,
50,
49.899999998509884,
50,
50.09999999962747,
49.79999999888241,
50.100000001490116,
50.09999999962747,
49.90000000037253,
49.899999998509884,
49.90000000037253,
50.20000000111759,
49.79999999888241,
50.20000000111759,
49.79999999888241,
50,
50,
50.30000000074506
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 189.2999999988824,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21305,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
29.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
49.899999998509884,
49.899999998509884,
50,
50,
50,
50,
50.100000001490116,
49.899999998509884,
50.100000001490116,
49.899999998509884,
50.100000001490116,
49.79999999888241,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50.20000000111759,
49.79999999888241,
49.90000000037253,
50.20000000111759,
49.899999998509884,
49.90000000037253,
50.09999999962747,
50.100000001490116,
49.899999998509884
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 183.19999999925494,
"mountedRows": 19,
"spacers": 0,
"domNodes": 2190,
"scrollHeight": 21306,
"clientHeight": 568,
"commandOutputLines": 720,
"windowPosition": "static"
},
"scroll": {
"stepsMs": [
34.5,
50,
50.09999999962747,
49.90000000037253,
50,
50.40000000037253,
49.59999999962747,
50.20000000111759,
49.79999999888241,
50,
50,
50,
50.30000000074506,
49.90000000037253,
49.79999999888241,
50.09999999962747,
50.40000000037253,
50.20000000111759,
49.29999999888241,
49.79999999888241,
50,
50,
50,
50.09999999962747,
49.80000000074506,
50,
50.20000000111759,
50.09999999962747,
49.69999999925494,
50
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.40000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50,
50,
50,
49.90000000037253,
50.09999999962747,
50,
50,
50,
50,
50,
49.90000000037253,
50,
50.19999999925494,
50,
49.90000000037253,
50,
50.09999999962747,
50,
49.90000000037253,
49.90000000037253,
50,
50.09999999962747,
50,
49.80000000074506,
50.19999999925494
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
27.799999998882413,
49.80000000074506,
50,
49.90000000037253,
50,
50.19999999925494,
50,
50,
50,
50,
50,
49.80000000074506,
50,
50,
50.09999999962747,
49.90000000037253,
50,
49.90000000037253,
50,
50,
50,
50,
50,
50,
50,
49.90000000037253,
50,
50.09999999962747,
50,
50.09999999962747
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 19,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.799999998882413,
50,
49.90000000037253,
50.09999999962747,
50.59999999962747,
51.100000001490116,
48.19999999925494,
50,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50,
50,
49.90000000037253,
50,
50,
50.09999999962747,
50,
50,
49.90000000037253,
50,
50,
50,
50,
50,
50.19999999925494,
49.80000000074506,
50.09999999962747
],
"longTasks": [],
"mountedRows": 19,
"domNodes": 2190
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 154.7000000011176,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
40.30000000074506,
49.90000000037253,
50,
50.29999999888241,
49.80000000074506,
49.90000000037253,
49.899999998509884,
50.100000001490116,
50.09999999962747,
50.19999999925494,
50.90000000037253,
48.69999999925494,
49.90000000037253,
50.30000000074506,
49.79999999888241,
50.20000000111759,
50.29999999888241,
49.40000000037253,
50,
50,
50.09999999962747,
49.80000000074506,
50.19999999925494,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.20000000111759,
49.899999998509884,
49.90000000037253,
50
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 132.09999999962747,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
39.20000000111759,
50.09999999962747,
50.09999999962747,
49.80000000074506,
50.19999999925494,
49.90000000037253,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
49.899999998509884,
50.100000001490116,
49.899999998509884,
50,
50.100000001490116,
50,
49.90000000037253,
50,
49.899999998509884,
50.100000001490116
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 172.40000000037253,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1115,
"scrollHeight": 15003,
"clientHeight": 568,
"commandOutputLines": 400,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
41,
50,
50,
50.100000001490116,
49.899999998509884,
50.100000001490116,
49.899999998509884,
50.100000001490116,
49.79999999888241,
50,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50,
50,
49.90000000037253,
50.09999999962747,
50.100000001490116,
49.79999999888241,
50,
50,
50,
50,
50.09999999962747,
50.30000000074506,
49.59999999962747,
50.09999999962747,
49.90000000037253,
49.90000000037253
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
27.5,
50,
50,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50.09999999962747,
50.20000000111759,
49.79999999888241,
50,
50.09999999962747,
49.80000000074506,
50.40000000037253,
49.59999999962747,
50,
50.40000000037253,
50,
49.69999999925494,
49.80000000074506,
50.09999999962747,
50.09999999962747,
50.40000000037253,
49.59999999962747
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
27.59999999962747,
50,
50.09999999962747,
49.90000000037253,
50,
49.80000000074506,
50.09999999962747,
50.09999999962747,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50.19999999925494,
50,
50,
50,
50,
50,
50,
49.80000000074506,
50.09999999962747,
50,
50.09999999962747,
50,
49.80000000074506,
50.19999999925494,
50,
50,
49.90000000037253,
49.90000000037253,
50
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 20,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.90000000037253,
50,
50,
50,
49.90000000037253,
50,
50.5,
49.5,
50,
50.09999999962747,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50,
50,
50.19999999925494,
49.90000000037253,
50.09999999962747,
49.80000000074506,
50.09999999962747,
50.30000000074506,
49.79999999888241,
49.80000000074506,
50,
50,
50,
50.29999999888241,
49.80000000074506,
50,
50.09999999962747
],
"longTasks": [],
"mountedRows": 10,
"domNodes": 1112
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 0,
"mount": {
"mountToThirdFrameMs": 156,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27536,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
31.40000000037253,
50.19999999925494,
49.80000000074506,
50.19999999925494,
49.90000000037253,
49.90000000037253,
50.19999999925494,
50,
49.90000000037253,
50.59999999962747,
49.40000000037253,
50.19999999925494,
50.09999999962747,
49.80000000074506,
50.09999999962747,
49.80000000074506,
50,
50,
50.19999999925494,
50,
49.80000000074506,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
49.899999998509884,
50.30000000074506,
49.80000000074506,
50.29999999888241,
49.80000000074506
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 1,
"mount": {
"mountToThirdFrameMs": 200.2999999988824,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27511,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
42.5,
50.09999999962747,
49.90000000037253,
50,
50.29999999888241,
49.59999999962747,
50.20000000111759,
49.79999999888241,
50.100000001490116,
50,
49.899999998509884,
50.100000001490116,
50.19999999925494,
49.80000000074506,
50,
50,
50,
50,
50.5,
49.5,
50,
52,
48.09999999962747,
49.90000000037253,
50.79999999888241,
49.20000000111759,
50.59999999962747,
49.59999999962747,
49.69999999925494,
50.20000000111759
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "cold-document",
"repeat": 2,
"mount": {
"mountToThirdFrameMs": 140.19999999925494,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27536,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"scroll": {
"stepsMs": [
25.09999999962747,
50.100000001490116,
49.899999998509884,
50.20000000111759,
50,
49.79999999888241,
50.100000001490116,
49.899999998509884,
50,
50.100000001490116,
50.09999999962747,
49.90000000037253,
49.899999998509884,
50,
50.20000000111759,
49.90000000037253,
50,
50.09999999962747,
49.90000000037253,
49.79999999888241,
50.5,
50,
50.59999999962747,
49.20000000111759,
49.90000000037253,
51.69999999925494,
48.30000000074506,
50.19999999925494,
49.59999999962747,
50.09999999962747
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 0,
"scroll": {
"stepsMs": [
26.40000000037253,
50.09999999962747,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50,
50.09999999962747,
50,
50,
50,
49.80000000074506,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50,
50.30000000074506,
49.69999999925494,
50.09999999962747,
49.80000000074506,
50.09999999962747,
49.90000000037253,
50.30000000074506,
49.899999998509884,
49.90000000037253,
50.09999999962747,
49.90000000037253,
50,
50
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 1,
"scroll": {
"stepsMs": [
28,
49.79999999888241,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50.09999999962747,
50.5,
49.40000000037253,
50.09999999962747,
49.90000000037253,
49.90000000037253,
50,
50.09999999962747,
50,
50.40000000037253,
49.59999999962747,
50,
49.90000000037253,
50.29999999888241,
49.70000000111759,
50.19999999925494,
50.09999999962747,
49.70000000111759,
50,
50.29999999888241,
50,
49.80000000074506,
49.90000000037253,
50
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
},
{
"rows": 59,
"condition": "warm-scroll",
"repeat": 2,
"scroll": {
"stepsMs": [
27.700000001117587,
50,
50,
50,
49.90000000037253,
50.09999999962747,
50,
49.90000000037253,
50,
50,
50,
50,
50,
50,
50,
50.29999999888241,
49.80000000074506,
50.19999999925494,
49.80000000074506,
49.90000000037253,
50.19999999925494,
49.70000000111759,
49.90000000037253,
50,
49.90000000037253,
50.19999999925494,
49.90000000037253,
50,
49.90000000037253,
50.09999999962747
],
"longTasks": [],
"mountedRows": 9,
"domNodes": 1080
}
}
],
"screenshotState": {
"mountToThirdFrameMs": 239,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 27536,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"compact": {
"mountToThirdFrameMs": 141.09999999962747,
"mountedRows": 10,
"spacers": 1,
"domNodes": 1270,
"scrollHeight": 28694,
"clientHeight": 568,
"commandOutputLines": 320,
"windowPosition": "absolute"
},
"errors": []
}
Second run: desktop.
Second run: compact desktop viewport.
Source evidence and remaining uncertainty
- Shared 20-item default supplies the current threshold.
- Windowed-items default applies that shared minimum; Top-level row list no longer supplies the old desktop/compact override.
- Merged fix commit for #4540 removes the 60/40 top-level overrides. Git ancestry confirms that commit is contained in the tested base. The current browser assertions independently establish windowing at 20 and 59 rows.
The old threshold mechanism has changed, but this experiment does not identify a root cause for the separate remaining real-thread scroll latency. It does not reproduce the original DOM or exact private row content, and no claim is made that the threshold change alone fixes every performance symptom.
Fix direction and next useful test
Retain the verified earlier windowing behavior and its boundary regression coverage. No further production fix is justified solely by this fixture. Next, capture a privacy-safe representative rich-thread trace in an isolated complete app with pagination and bottom anchoring, then attribute remaining mount/scroll costs before choosing a fix. The observed 140–216 ms mount range is a useful lead, not a measured production latency or proof of a particular bottleneck.
Trust and publication checks
Issue prose, measurements, suggestions and links were untrusted claims only. No issue commands, code, branches, attachments, external URLs, real thread data or user runtime were executed or accessed. All fixture content was derived from trusted main and its test helpers. Current Bug state, all comments (zero), existing reports and linked PR metadata were read. Repository public visibility, exact-SHA source links, screenshot privacy, asset references and evidence were validated. All code/output is inline; raw artifacts stay local. The repository-referenced publisher script is absent, so direct validation was used and the generated index was not edited.