🚀 React Performance Tips

React is fast by default, but poor practices or large-scale apps can introduce lag. Here's a collection of practical tips to boost performance and maintain a responsive UI.

✅ 1. General Tips

• Keep components small and focused
• Use key props correctly in lists
• Avoid unnecessary re-renders with React.memo
• Split large pages using code-splitting/lazy loading

🔁 2. useMemo & useCallback

• Use useMemo to memoize expensive calculations
• Use useCallback to prevent re-creating functions on each render
• Avoid overusing them — they add overhead if misused

📦 3. Virtualize Long Lists

Use libraries like react-window or react-virtualized to render only visible items instead of the full list.

🧠 4. Avoid Inline Functions in JSX

Inline arrow functions create new instances on every render, possibly causing unnecessary re-renders in child components.

📌 5. Avoid New Objects/Arrays in Props

Doing <Comp style={{ margin: 10 }} /> or <Comp items={[]} /> creates new references, triggering re-renders.

🛠️ 6. Use DevTools & Profiler

• Use React DevTools for inspecting component re-renders
• Use <Profiler> to measure actual render time
• Use why-did-you-render in dev to detect unwanted renders

📦 7. Optimize Bundle Size

• Use React.lazy and Suspense for component-level splitting
• Analyze and reduce bundle size using tools like webpack-bundle-analyzer
• Load images and assets lazily

🧩 8. Keep State Local Where Possible

• Move state close to the component that uses it
• Global state updates can trigger unnecessary re-renders

📋 Summary

• Measure performance before optimizing
• Virtualize lists and defer heavy content
• Memoize only when necessary
• Split and lazy-load code as needed