React.memo and Performance Optimization

React re-renders can slow down applications. Here's how to optimize with memoization.

Best Practices#

When to Use:
✓ Expensive computations
✓ Components with many children
✓ Callbacks passed to memoized children
✓ Context values
✓ Virtualized lists

When to Skip:
✓ Simple/cheap operations
✓ Props that always change
✓ Components that rarely re-render
✓ Small component trees

Debugging:
✓ Use React DevTools Profiler
✓ Add console.logs to track renders
✓ Use why-did-you-render in development
✓ Measure before optimizing

Patterns:
✓ Move state down
✓ Lift content up
✓ Split contexts
✓ Use refs for callbacks

React.memo, useMemo, and useCallback prevent unnecessary re-renders when used correctly. Profile first to identify actual performance issues, then apply memoization strategically. Over-optimization adds complexity without benefits. Focus on component composition patterns and virtualization for the biggest performance gains.

React.memo and Performance Optimization

Understanding Re-renders#

React.memo Basics#

useCallback for Functions#

useMemo for Values#

Common Patterns#

Component Composition#

Virtualization#

Profiling Performance#

When NOT to Memoize#

Advanced Patterns#

Best Practices#

Conclusion#

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