orca/docs/performance-audit.md

Orca Performance Audit

Audit date: 2026-04-13 Branch: Jinwoo-H/performance-improvement

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Tier 1 — High Impact, Low Complexity

#	Area	Issue	File(s)	Status
1	Renderer	App.tsx has 53 separate Zustand subscriptions — nearly every state change re-renders the root and cascades through the entire tree	src/renderer/src/App.tsx:40-180	DONE (53→22 subs, memo barriers on 4 children)
2	Renderer	Terminal.tsx has unscoped useAppStore.subscribe() — fires on every store mutation, does O(worktrees×tabs) scan each time	src/renderer/src/components/Terminal.tsx:645-659	DONE
3	Terminal	No IPC batching — every PTY data chunk is a separate webContents.send call, hundreds/sec under load	src/main/ipc/pty.ts:173-177	DONE
4	Terminal	Divider drag calls fitAddon.fit() on every pointermove pixel — xterm reflow can take 500ms+ with large scrollback	src/renderer/src/lib/pane-manager/pane-divider.ts:90-119	DONE
5	Main	Startup blocks: openCodeHookService.start() and runtimeRpc.start() awaited sequentially before window opens	src/main/index.ts:131-168	DONE
6	Main	persistence.ts uses readFileSync/writeFileSync/renameSync on the main thread — blocks during startup and every 300ms save	src/main/persistence.ts:59-125	DONE
7	Worktree	worktrees:listAll iterates repos sequentially with await — total time = sum of all repos instead of max	src/main/ipc/worktrees.ts:53-84	DONE
8	Browser	Reverse Map scan O(N) on every mouse/load/permission event in BrowserManager	src/main/browser/browser-manager.ts:91-96	DONE
9	Browser	before-mouse-event listener fires for ALL mouse events on ALL guests, even background ones	src/main/browser/browser-guest-ui.ts:78-93	DONE
10	Worktree	refreshGitHubForWorktree bypasses 5-min cache TTL on every worktree switch — fires GitHub API calls on rapid tab switching	src/renderer/src/store/slices/worktrees.ts:467-489	DONE

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Tier 2 — Medium Impact

#	Area	Issue	File(s)	Status
11	Main	git/repo.ts: execSync('gh api user ...') and chains of 5 sync git processes block main thread	src/main/git/repo.ts:87-138	TODO
12	Main	hooks.ts: readFileSync/writeFileSync/mkdirSync/gitExecFileSync in IPC handlers	src/main/hooks.ts:113-416	TODO
13	Renderer	useSettings returns entire GlobalSettings (~30+ fields) — any setting change re-renders all consumers	src/renderer/src/store/selectors.ts	TODO
14	Renderer	Tab title changes bump sortEpoch for ALL worktrees → triggers WorktreeList re-sort on every PTY title event	src/renderer/src/store/slices/terminals.ts:325	TODO
15	Renderer	CacheTimer: one setInterval per mounted card (20 cards = 20 intervals/sec), each with O(n) selector work	src/renderer/src/components/sidebar/CacheTimer.tsx:28-48	TODO
16	Renderer	Three simultaneous 3-second polling intervals per active worktree (git status, worktrees, stale conflict)	src/renderer/src/components/right-sidebar/useGitStatusPolling.ts	TODO
17	Renderer	6 components missing React.memo: SourceControl, RightSidebar, EditorPanel, ChecksPanel, FileExplorer, TabBar	Various files in src/renderer/src/components/	DONE (8 components wrapped)
18	Worktree	Git polling fires immediately on every worktree switch (burst of git status + git worktree list)	src/renderer/src/components/right-sidebar/useGitStatusPolling.ts:69-103	REVERTED (150ms debounce caused visible flash on switch)
19	Worktree	FileExplorer dirCache discarded on every worktree switch — re-fetches entire tree from scratch	src/renderer/src/components/right-sidebar/useFileExplorerTree.ts:27,81-96	TODO
20	Terminal	pty:resize uses ipcRenderer.invoke (round-trip) instead of fire-and-forget send	src/preload/index.ts:203-205	DONE
21	Terminal	Flow control watermarks defined but never enforced for local PTYs — unbounded output floods renderer	src/main/providers/local-pty-provider.ts:330-332	TODO
22	Browser	BrowserPane subscribes to entire browserPagesByWorkspace map — any tab's navigation re-renders all panes	src/renderer/src/components/browser-pane/BrowserPane.tsx:312	TODO
23	Browser	findPage/findWorkspace do O(N) Object.values().flat().find() scans on every navigation event	src/renderer/src/store/slices/browser.ts:221-240	TODO
24	Browser	Download progress IPC fires at full Chromium frequency (many/sec)	src/main/browser/browser-manager.ts:421-430	TODO
25	Main	detectConflictOperation runs 4 existsSync + readFile on every 3s poll before git status	src/main/git/status.ts:236-265	DONE
26	Main	getBranchCompare: loadBranchChanges and countAheadCommits run sequentially	src/main/git/status.ts:374-375	DONE
27	Main	addWorktree calls 4-5 synchronous git processes from IPC handler	src/main/git/worktree.ts:116-157	DONE

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Tier 3 — Lower Impact / Architectural

#	Area	Issue	File(s)	Status
28	Terminal	SSH relay FrameDecoder uses Buffer.concat on every chunk (quadratic copy)	src/relay/protocol.ts:84	TODO
29	Terminal	SSH relay replay buffer uses string concatenation (quadratic allocation)	src/relay/pty-handler.ts:68-72	TODO
30	Terminal	extractLastOscTitle regex runs on every PTY chunk with no fast-path bail	src/shared/agent-detection.ts:23-39	TODO
31	Terminal	Binary search calls serialize() up to 16× at shutdown	src/renderer/src/components/terminal-pane/TerminalPane.tsx:579-596	TODO
32	Browser	capturePage() captures full viewport then crops — should pass rect directly	src/main/browser/browser-grab-screenshot.ts:36	TODO
33	Browser	Parked webviews retain full 100vw×100vh compositor surfaces	src/renderer/src/components/browser-pane/BrowserPane.tsx:94-107	TODO
34	Browser	onBeforeSendHeaders intercepts every HTTPS request even when UA override unused	src/main/browser/browser-session-registry.ts:126-137	TODO
35	Main	setBackgroundThrottling(false) wastes CPU when window is minimized	src/main/window/createMainWindow.ts:97	TODO
36	Main	warmSystemFontFamilies() competes with startup I/O	src/main/system-fonts.ts:30-32	TODO
37	Renderer	Session persistence effect has 15 deps — fires on every tab title change	src/renderer/src/App.tsx:239-283	TODO
38	Renderer	Per-card fetchPRForBranch on mount — 30 worktrees = 30 simultaneous IPC calls	src/renderer/src/components/sidebar/WorktreeCard.tsx:128-132	TODO
39	Renderer	Synchronous full monaco-editor import blocks EditorPanel chunk evaluation	src/renderer/src/components/editor/EditorPanel.tsx:7	TODO
40	Worktree	removeWorktree runs git worktree list twice (pre and post removal)	src/main/git/worktree.ts:163-208	TODO
41	Worktree	worktrees:list can trigger duplicate git worktree list when cache is dirty	src/main/ipc/worktrees.ts:86-116	TODO
42	Renderer	SSH targets initialized sequentially in a for...await loop	src/renderer/src/hooks/useIpcEvents.ts:232-252	TODO

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Key Themes

1. Zustand subscription granularity — App.tsx subscribes to 53 slices, Terminal.tsx subscribes to everything, useSettings returns the full object. Almost any state change cascades through the entire tree.

2. Synchronous I/O on the main thread — persistence.ts, hooks.ts, git/repo.ts, and git/worktree.ts use readFileSync/writeFileSync/execSync in startup and IPC handler paths.

3. Unthrottled high-frequency events — PTY data (no IPC batching), divider drag (fit on every pixel), download progress (no throttle), before-mouse-event (all mouse events on all guests), CacheTimer (20 intervals/sec).

4. Sequential operations that could be parallel — Startup server binds, repo iteration in listAll, git ref probing, loadBranchChanges/countAheadCommits, SSH target init.

5. Aggressive polling — Three 3-second intervals per worktree, per-card 1-second cache timers, per-card 5-minute issue polling, 250ms error-page detection.