edadfcae96
TreeGroup called useStore($layoutTree) to build its right-click menu's move/split directions. That subscribes every zone — and therefore every mounted pane and its entire transcript — to the whole layout tree. A sash drag rewrites the tree once per frame, so dragging the sidebar re-rendered all five tiles' message lists on every pointermove, for a context menu nobody had open. The directions are only read when the menu renders, so read the tree there with .get() instead. Same lazy shape the neighbouring `closable` prop already uses. Measured over one 60px sash drag with five busy tiles: commits 83 -> 12 ChatView 150 -> 10 (4465ms -> 353ms) AuiProvider 9450 -> 630 (9868ms -> 774ms) TreeGroup 180 -> 12 TreeSplit 90 -> 6 Also fixes an observer effect in the harness: idle-cost recorded render attribution *during* the timed gesture, and the counter walks the fiber tree on every commit. That was large enough to hide this 15x reduction behind an unchanged fps, so timing and attribution are separate passes now and `record` defaults off. Adds scripts/diag-drag-churn.mjs — the probe that found this. It reports the transcript chain (who above the messages re-rendered) plus every atom that notified, which is what named TreeGroup instead of leaving it to be guessed at. Notably the atom list came back EMPTY: this was never store churn, so the render-attribution path was the only thing that could have found it. |
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| .. | ||
| lib | ||
| scenarios | ||
| baseline.json | ||
| README.md | ||
| run.mjs | ||
| serve.mjs | ||
Desktop perf harness
One systematized way to measure desktop rendering/interaction performance,
diff it against a committed baseline, and fail on regressions. It replaces the
dozen one-off measure-* / profile-* scripts that each reinvented the CDP
client, arg parsing, stats, and output (and never had a baseline).
Quick start
# Isolated instance (recommended) — no running app or LLM credits needed.
# Its own --user-data-dir + HERMES_HOME means it never collides with `hgui`.
npm run perf -- --spawn
# Or: launch an isolated instance once, attach repeatedly (faster iteration).
npm run perf:serve # leaves an instance on :9222
npm run perf # attaches, runs the CI suite, gates on baseline
# One scenario, with a CPU profile:
npm run perf -- stream --cpuprofile --tokens 800
# Representative PRODUCTION numbers (minified React, not the ~3x-slower dev build):
npm run perf -- cold-start stream keystroke transcript --spawn --prod
# Re-capture the baseline on your reference device, then commit baseline.json:
npm run perf -- cold-start stream keystroke transcript --spawn --prod --update-baseline
Dev vs prod
By default the harness measures the dev renderer (fast to spin up, good for
relative regression checks). Pass --prod (with --spawn) to build a
production renderer with the probe included (VITE_PERF_PROBE=1) and measure
minified React — the representative shipped numbers. The committed baseline is
captured with --prod.
Why isolation matters
The measurement this harness exists to run was historically blocked: a running
hgui holds the Electron single-instance lock, so a second instance quit
immediately. --spawn / perf:serve launch with their own --user-data-dir
(separate lock scope), their own HERMES_HOME (separate backend + sessions),
and their own --remote-debugging-port. Synthetic scenarios drive $messages
directly via window.__PERF_DRIVE__, so no LLM credits are spent.
Scenarios
| scenario | tier | measures | replaces |
|---|---|---|---|
stream |
ci | streaming longtasks, frame p95/p99, mutation cadence | measure-synthetic-stream, profile-synth-stream, profile-long-stream |
stream --real |
backend | same, from a real LLM stream | measure-real-stream, profile-real-stream |
keystroke |
ci | composer keystroke → paint latency | measure-latency, profile-typing, leak-typing |
transcript |
ci | large-transcript mount + paint cost | (new) |
render-churn |
ci | per-component render attribution + store churn while N tabs stream | (new) |
cold-start |
cold | launch → CDP → driver → first paint (fresh spawn/run) | (new) |
first-token |
backend | Enter → first assistant token painted (TTFT) | (new) |
submit |
backend | Enter → cleared → user msg painted, scroll jump | measure-submit, measure-jump |
session-switch |
backend | route → first-paint → settle | profile-session-switch |
profile-switch |
backend | rail click → sidebar settled | measure-profile-switch |
ci + cold scenarios need no backend/credits and are gated against
baseline.json (cold-start requires --spawn since it measures a fresh
launch, and must be run in its own invocation). backend scenarios need a live
backend (and --spawn or a real session/credits) and are report-only.
CPU profiling is a cross-cutting --cpuprofile flag on any scenario (it wraps
the run in Profiler.start/stop and prints a top-self-time table), replacing
every standalone profile-* script.
Adding a scenario
Create scenarios/<name>.mjs exporting { name, tier, description, run(cdp, opts) }
where run returns { metrics, detail } (metrics = flat numbers, lower is
better), then register it in scenarios/index.mjs. If it's ci, add a
baseline.json entry (or run --update-baseline).
Layout
lib/cdp.mjs— the one CDP client + target discovery + typing + CPU-profile wrapper + DOM selectors.lib/stats.mjs— percentiles, histograms, CPU-profile self-time ranking.lib/baseline.mjs— load/compare/update the baseline + regression gate.lib/launch.mjs— attach, or spawn a fully isolated instance.scenarios/— one module per measurement.run.mjs— entrypoint.serve.mjs— standalone isolated launcher.
Not migrated (kept as dev utilities)
eval.mjs, reload.mjs, reload-renderer.mjs, probe-renderer.mjs,
probe-thread.mjs, click-session.mjs, diag-*.mjs are interactive dev
helpers, not benchmarks. They can adopt lib/cdp.mjs in a follow-up.