React applications can suffer from performance issues as they grow. This guide covers proven techniques to keep your React apps fast and responsive.
Understanding React Rendering
React re-renders components when state or props change. Understanding the rendering lifecycle is crucial for optimization. Unnecessary re-renders are the most common performance bottleneck.
Memoization with useMemo and useCallback
useMemo caches expensive computations, while useCallback memoizes functions to prevent unnecessary re-renders of child components.
const expensiveValue = useMemo(() => {
return computeExpensiveValue(data);
}, [data]);
const handleClick = useCallback(() => {
doSomething(id);
}, [id]);Code Splitting and Lazy Loading
Split your bundle into smaller chunks that load on demand. React.lazy and Suspense enable component-level code splitting.
const Dashboard = lazy(() => import('./Dashboard'));
function App() {
return (
<Suspense fallback={<Loading />}>
<Dashboard />
</Suspense>
);
}Virtualization for Long Lists
Rendering thousands of items kills performance. Use virtualization libraries like react-window to render only visible items.
Conclusion
Performance optimization is an ongoing process. Profile your application, identify bottlenecks, and apply these techniques where they provide the most impact.
Key Takeaways
Profile before optimizing - measure the impact
Memoization prevents unnecessary re-renders
Code splitting reduces initial bundle size
Virtualize long lists and tables
Use React DevTools Profiler to identify bottlenecks