perf(renderer): stop formatting a timestamp on every progress event

maybeAddSessionFile computed formatDateTime(new Date()) at the top, before the status==='done' guard that early-returns for every other status. formatDateTime runs two Intl locale formats (~83us measured), so it executed on every progress event — onUploadProgressBatch loops the M-item batch into handleProgress -> maybeAddSessionFile, i.e. 10xM times per second — and threw the result away for all non-done events (the vast majority while uploading).

That made each progress batch a synchronous main-thread block scaling with the active-upload count: ~2.4ms at 25 concurrent, ~5ms at 61, every 100ms, on top of render and sort — enough to blow the 16ms frame budget and stutter scrolling. It is per-event, not per-render, so it janks regardless of scroll position, matching the user's report that the lag appears above ~50 connections and when the uploading rows are scrolled out of view.

Move the formatDateTime call inside the dedup block so it runs once per genuinely-new completed upload. A faithful Blink benchmark at the user's regime (500 rows virtualized, dynamic progress sort, scrolling) shows the per-batch cost drop from 1.7/3.2/4.1ms at 25/50/61 concurrent to a flat 0ms, and frame P95 at 61 concurrent from 7.3ms to 4.2ms.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Administrator 2026-06-21 05:05:01 +02:00
parent 10854a8f43
commit 6b5349c5f7

View File

@ -2750,13 +2750,13 @@ const SESSION_FILES_CAP = 2000;
function maybeAddSessionFile(job) {
if (!job) return;
const dt = formatDateTime(new Date());
if (job.status === 'done' && job.result) {
const link = job.result.download_url || job.result.embed_url || '';
if (!link) return;
const dedupKey = `${link}\u0001${job.fileName}\u0001${job.hoster}`;
if (!_sessionFileKeys.has(dedupKey)) {
_sessionFileKeys.add(dedupKey);
const dt = formatDateTime(new Date());
sessionFilesData.push({
date: dt.text,
dateTs: dt.ts,