⚡ Bolt: React Performance & State Optimization#528
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- Memoize all Context Provider values and functions to reduce unnecessary re-renders. - Replace redundant `useState`/`useEffect` with derived state in `Chat.tsx`. - Fix `MapDataProvider` shadowing bug by moving provider to page level and removing redundant instances. - Document performance patterns in `.jules/bolt.md`. Co-authored-by: ngoiyaeric <115367894+ngoiyaeric@users.noreply.github.com>
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Overall the changes are directionally good and should reduce rerenders. A few hooks have avoidable maintainability pitfalls: toggleCalendar should include startTransition in its useCallback deps, MapLoadingProvider adds an unnecessary wrapper around a stable state setter, and MapDataProvider’s useMemo deps should be made consistent (or explicitly justified).
Additional notes (3)
- Maintainability |
components/calendar-toggle-context.tsx:21-33
toggleCalendarcloses overstartTransitionbut the callback has an empty dependency array. This is usually stable, but it’s safer and clearer to includestartTransitionin the deps so the hook is correct even if React changes stability guarantees or this code is refactored.
Also, memoizing the context value is good, but you can simplify the dependency list by ensuring the callback deps are correct.
- Readability |
components/map-loading-context.tsx:11-22
setIsMapLoadedCallbackis just a thin wrapper over thesetIsMapLoadedstate setter. React guarantees state setters are stable, so this extra callback adds complexity without benefit.
You can still keep value memoization, but avoid wrapping stable setters unless you’re transforming inputs or adding logic.
- Maintainability |
components/map/map-data-context.tsx:41-52
The memoizedvalueomitssetMapDatafrom the dependency array. While React state setters are stable (so this likely won’t break), this relies on that implicit guarantee and makes the memoization pattern inconsistent with other providers in the codebase.
Either include setMapData for consistency, or document why it’s intentionally omitted.
Summary of changes
Summary
This PR focuses on reducing unnecessary React re-renders and fixing a context-provider layering issue.
✅ React context performance improvements
- Memoized provider
valueobjects withuseMemoacross multiple contexts:components/calendar-toggle-context.tsxcomponents/history-toggle-context.tsxcomponents/map-loading-context.tsxcomponents/map-toggle-context.tsxcomponents/map/map-data-context.tsxcomponents/profile-toggle-context.tsxcomponents/usage-toggle-context.tsx
- Memoized context actions with
useCallback(e.g.,toggleCalendar,toggleHistory,setMapType).
✅ Chat render-path simplification
- In
components/chat.tsx, replaceduseState+useEffectforshowEmptyScreenwith derived render-time state:const showEmptyScreen = messages.length === 0.
✅ Provider shadowing removal
- Removed
MapDataProviderusage fromcomponents/chat.tsx(both mobile and desktop branches) to avoid shadowing a higher-level provider and reduce tree depth.
📝 Documentation
- Added a journal entry in
.jules/bolt.mddocumenting provider shadowing and context memoization guidance.
2 participants
Identified and implemented multiple performance improvements focused on React re-render reduction and state efficiency.
Key changes:
useMemoanduseCallbackto all toggle and data context providers. This prevents all consumers from re-rendering every time the provider's parent updates, unless the actual state they consume has changed.Chat.tsx, replaced a redundantuseState+useEffectloop forshowEmptyScreenwith a direct calculation during render, saving one render cycle on every message update.MapDataProviderfromChat.tsxthat was shadowing the page-level provider, ensuring a single source of truth for map data and reducing component tree depth.These changes combined make the application UI feel more responsive, especially during active chat streaming and map interactions.
PR created automatically by Jules for task 3777408721638993864 started by @ngoiyaeric