React Re-rendering Causing Performance Issues - Slow Interactions
Your app feels sluggish when interacting. Typing in inputs lags, clicking buttons is unresponsive. React is re-rendering too much.
Frame rate drops during interactions or when state updates happen.
Error Messages You Might See
Common Causes
- Parent component re-rendering, causing all children to re-render unnecessarily
- Heavy computations happening during render
- State updates too frequently or on every keystroke without debounce
- Missing useMemo or useCallback, causing child components to re-render
- Large lists rendering all items instead of virtualizing
How to Fix It
Use React DevTools Profiler to identify slow components
Memoize expensive computations: useMemo(() => expensiveCalc(data), [data])
Memoize callbacks: useCallback(fn, deps) to prevent child re-renders
Use React.memo for components that receive same props
Debounce input: useDebounce(value, 300) for search/filters
Virtualize long lists: react-window or react-virtualized
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Get HelpFrequently Asked Questions
How do I know if component is re-rendering too much?
React DevTools Profiler - record interaction, see render counts. Add console.log to component
Should I memoize everything?
No, adds overhead. Only memoize expensive calculations or passed-to-children functions
What's the difference between useMemo and useCallback?
useMemo caches computed value. useCallback caches function reference. Both prevent unnecessary re-renders of children