What is the first rule of React performance optimization?
Measure before optimizing. Do not guess what is slow. Use the React DevTools Profiler to find which components are slow or re-render too much, then optimize those specifically.
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More FAQs in React Performance Optimization Techniques That Actually Matter
When a component does expensive computation on every render. Wrapping that computation in useMemo means it only recomputes when its dependencies change. This is one of the few memoization cases that clearly helps.
Stabilize prop references. If a parent passes new object or function references on every render, children re-render even if nothing changed. Use useMemo and useCallback to stabilize references, or pass primitive props where possible.
Virtualize it. Rendering thousands of items at once is slow. Use a virtualization library like react-window to render only the visible items, which dramatically improves list performance.
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