Finalize part3 performance pass with Worker preprocessing, WebAssembly note math, and activation diagnostics by Copilot · Pull Request #16 · 7effrey89/PianoHero

Copilot · 2026-05-17T08:36:14Z

This PR completes the remaining optimization work from the prior performance pass by offloading heavy note preprocessing and adding a WebAssembly-backed fast path for repeated note-height math. Existing GPU note rendering remains in place and is now paired with lower main-thread preprocessing cost, plus runtime diagnostics to verify optimization activation.

Web Worker offload for song preprocessing
- Added performance-worker.js to precompute:
  - BPM estimate
  - simple-mode merged notes
  - normal/simple song durations
- app.js now asynchronously requests this precompute during song load/upload flows and applies cached outputs in applyGameMode().
- Worker request handling now includes pending-cleanup on postMessage failure and request timeout handling to avoid stuck pending tasks.
WebAssembly hot-path optimization
- Added note-math.wasm with exported math functions for note height calculation.
- Added wasm bootstrap + safe JS fallback in app.js.
- Replaced repeated Math.max(12, dur * noteSpeed * speed...) logic in hot render/update paths with shared helpers.
Mode/duration caching integration
- Introduced _simpleModeCache and _durationCache to avoid recomputing merged-note timelines on mode switches.
- applyGameMode() now consumes cached precompute output when available.
Activation/verification diagnostics
- Added live runtime status text in UI (settings + header) to show:
  - Worker status (init/ready/error/unsupported)
  - WASM status (init/ready/error/fetch-failed/unsupported)
  - Precompute mode (worker/mixed/fallback) and elapsed time
- Added console timing logs for each precompute run to make optimization behavior measurable on real songs.
Asset wiring
- Bumped app.js cache-bust version in index.html to pick up runtime changes.

// Worker-backed precompute on load
this.originalNotes = data.notes;
await this._precomputeSongData(data.notes);
this.applyGameMode();

// WASM-backed hot-path helper with fallback
_visibleNoteHeight(duration, speedMultiplier) {
  const dur = duration || 0.15;
  if (this._wasmMath?.note_visible_height) {
    return this._wasmMath.note_visible_height(dur, this.noteSpeed, speedMultiplier);
  }
  return Math.max(12, dur * this.noteSpeed * speedMultiplier);
}

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/6d3fb3f9-ff53-4148-8d93-687ef6486650 Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot

Pull request overview

This PR completes the “part3 performance pass” by moving song preprocessing work off the main thread into a Web Worker and introducing a WebAssembly-backed fast path for repeated note-height calculations during rendering.

Changes:

Added performance-worker.js to precompute BPM, merged notes for simple mode, and durations in a worker.
Updated app.js to request/apply worker-precomputed caches and to use WASM-backed helpers (with JS fallback) for note height math.
Bumped app.js cache-bust version in index.html.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
performance-worker.js	New worker that precomputes BPM, simple-mode merged notes, and durations.
app.js	Initializes worker + WASM, adds caches for precompute output, and routes hot-path note height math through shared helpers.
index.html	Updates `app.js` query-string version to pick up the runtime changes.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

+    async _precomputeSongData(notes) {
+        const safeNotes = Array.isArray(notes) ? notes : [];
+        this._simpleModeCache = null;
+        this._durationCache = null;
+        let bpm = this.estimateBPM(safeNotes);
+        let normalDuration = 0;
+        for (let i = 0; i < safeNotes.length; i++) {
+            const n = safeNotes[i];
+            const end = n.time + (n.duration || 0.15);
+            if (end > normalDuration) normalDuration = end;
+        }


+        return new Promise((resolve, reject) => {
+            const id = ++this._perfWorkerReqId;
+            this._perfWorkerPending.set(id, { resolve, reject });
+            this._perfWorker.postMessage({ id, task, payload });


7effrey89 · 2026-05-17T12:57:25Z

@copilot Fix according to the pr reviews

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/e48db5e3-aec8-46a0-995d-79eb8be859eb Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot · 2026-05-17T13:00:24Z

@copilot Fix according to the pr reviews

Implemented the review fixes in e680cc2.

_runPerfWorkerTask() now cleans pending entries on postMessage failure and adds a timeout so requests can’t stay pending indefinitely.
_precomputeSongData() now avoids the duplicate upfront O(n) main-thread scans and only performs synchronous BPM/duration loops in fallback paths when worker output is unavailable/incomplete.

I couldn’t attach a UI screenshot here because the Playwright browser profile is locked in this environment (mcp-chrome lock error).

7effrey89 · 2026-05-17T14:10:54Z

@copilot

i do not experience a significant performance improvement for songs with many nodes like the one on the screenshot (pokemon theme.mid).

how would we verify that all the optimizations have been implemented and activated?

Copilot · 2026-05-17T14:12:07Z

@copilot

i do not experience a significant performance improvemen...

Good callout — with dense songs, the biggest cost can still be per-frame draw/update work, so load-time optimizations may feel subtle during playback.

To verify optimizations are active right now:

Worker path active

DevTools → Network: confirm performance-worker.js?v=1 loads.
DevTools → Sources: a dedicated Worker thread should appear.
Record a Performance trace while loading a heavy MIDI: main thread should not spend most preload time inside simplify/duration loops.

WASM path active

DevTools → Network: confirm note-math.wasm?v=1 loads (200).
In a Performance trace during playback, JS self-time in note-height math should be reduced vs pure JS fallback.

Fallback detection

If worker/wasm fail, code silently falls back to JS. In DevTools, failed requests for performance-worker.js or note-math.wasm indicate fallback is being used.

If you want, I can add a small debug indicator (e.g., in settings or console) showing Worker: on/off and WASM: on/off plus precompute timing, so activation is explicit and measurable on your machine.

7effrey89 · 2026-05-17T14:37:19Z

@copilot yws please do that

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/603cfdde-d889-4273-b67b-29725238cc9f Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot · 2026-05-17T14:43:24Z

@copilot yws please do that

Implemented in 62f47ee.

Added a live diagnostics indicator showing Worker/WASM activation state and precompute mode/time, plus console timing logs per precompute run.

7effrey89 · 2026-05-17T18:46:31Z

ADD to features and readme about all these optimization from previous and current pr and how to verify their activation @copilot

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/4d64e3dc-10f1-4dff-8bff-0553a6f3c2fe Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot · 2026-05-17T18:47:54Z

ADD to features and readme about all these optimization from previous and current pr and how to verify their activation @copilot

Implemented in b4419d7.

Added documentation in both README.md and features.md covering the optimization stack (Worker preprocessing, WASM note math, cache reuse, diagnostics) and clear activation verification steps (UI perf indicator, console timing logs, and optional DevTools network checks).

Initial plan

d24c11c

Copilot AI assigned Copilot and 7effrey89 May 17, 2026

Copilot started work on behalf of 7effrey89 May 17, 2026 08:36 View session

Copilot AI linked an issue May 17, 2026 that may be closed by this pull request

part3 performance #15

Closed

perf: add worker preprocessing and wasm note math helpers

820f880

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/6d3fb3f9-ff53-4148-8d93-687ef6486650 Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add Web Worker offload for performance improvements~~ Finalize part3 performance pass with Worker preprocessing and WebAssembly note math May 17, 2026

Copilot AI requested a review from 7effrey89 May 17, 2026 08:42

Copilot finished work on behalf of 7effrey89 May 17, 2026 08:42

7effrey89 requested a review from Copilot May 17, 2026 12:51

Copilot started reviewing on behalf of 7effrey89 May 17, 2026 12:51 View session

Copilot AI reviewed May 17, 2026

View reviewed changes

Copilot started work on behalf of 7effrey89 May 17, 2026 12:57 View session

fix: address worker fallback and pending cleanup review feedback

e680cc2

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/e48db5e3-aec8-46a0-995d-79eb8be859eb Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot finished work on behalf of 7effrey89 May 17, 2026 13:00

Copilot started work on behalf of 7effrey89 May 17, 2026 14:11 View session

Copilot finished work on behalf of 7effrey89 May 17, 2026 14:12

Copilot started work on behalf of 7effrey89 May 17, 2026 14:37 View session

feat: add perf optimization activation diagnostics

62f47ee

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/603cfdde-d889-4273-b67b-29725238cc9f Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot AI changed the title ~~Finalize part3 performance pass with Worker preprocessing and WebAssembly note math~~ Finalize part3 performance pass with Worker preprocessing, WebAssembly note math, and activation diagnostics May 17, 2026

Copilot finished work on behalf of 7effrey89 May 17, 2026 14:43

Copilot started work on behalf of 7effrey89 May 17, 2026 18:46 View session

docs: add optimization and activation verification guide

b4419d7

Agent-Logs-Url: https://github.com/7effrey89/PianoHero/sessions/4d64e3dc-10f1-4dff-8bff-0553a6f3c2fe Co-authored-by: 7effrey89 <30802073+7effrey89@users.noreply.github.com>

Copilot finished work on behalf of 7effrey89 May 17, 2026 18:48

7effrey89 added 8 commits May 17, 2026 21:18

small ui improvements - feedback bug

acd3530

bugfix

cd646f3

doc

229c421

starbust

61120da

neon glow

90d3066

feedback consolidated

24425e5

combo

9cc0c5e

speed widget

5396344

7effrey89 merged commit 5396344 into main May 31, 2026

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Finalize part3 performance pass with Worker preprocessing, WebAssembly note math, and activation diagnostics#16

Finalize part3 performance pass with Worker preprocessing, WebAssembly note math, and activation diagnostics#16
7effrey89 merged 13 commits into
mainfrom
copilot/add-web-worker-offload

Copilot AI commented May 17, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

Copilot AI commented May 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

7effrey89 commented May 17, 2026

Uh oh!

Copilot AI commented May 17, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Copilot AI commented May 17, 2026 •

edited

Loading