React Performance Optimization: Stop Re-rendering Everything

React Performance Optimization: Stop Re-rendering Everything

React is fast, but it can get slow if you're not careful. Let's learn how to keep your React apps lightning-fast with proper optimization techniques.

The Performance Problem

React re-renders components when:

• State changes
• Props change
• Parent component re-renders

The issue? Unnecessary re-renders waste CPU cycles and slow down your app.

React.memo: Prevent Unnecessary Re-renders

Without React.memo

Loading code...

With React.memo

Loading code...

Custom Comparison Function

Loading code...

useMemo: Memoize Expensive Calculations

Without useMemo

Loading code...

With useMemo

Loading code...

useCallback: Memoize Functions

The Problem

Loading code...

The Solution

Loading code...

Code Splitting: Load What You Need

Route-Based Splitting

Loading code...

Component-Based Splitting

Loading code...

Virtualization: Render What's Visible

Without Virtualization (Slow)

Loading code...

With Virtualization (Fast)

Loading code...

Debouncing and Throttling

Debounce: Wait for User to Stop Typing

Loading code...

Throttle: Limit Function Calls

Loading code...

Context API Optimization

The Problem

Loading code...

The Solution: Split Contexts

Loading code...

Image Optimization

Loading code...

Performance Checklist

• ✅ Use React.memo for expensive components
• ✅ Use useMemo for expensive calculations
• ✅ Use useCallback for function props
• ✅ Implement code splitting for routes
• ✅ Use virtualization for long lists
• ✅ Debounce/throttle event handlers
• ✅ Split Context into smaller contexts
• ✅ Lazy load images
• ✅ Use production build
• ✅ Profile with React DevTools

When NOT to Optimize

❌ Don't optimize prematurely ❌ Don't use useMemo for simple calculations ❌ Don't use React.memo for all components ❌ Don't over-split contexts

Rule of thumb: Optimize when you measure a performance problem, not before.

Measuring Performance

Loading code...

Conclusion

React performance optimization is about finding the right balance:

• Profile first, optimize later
• Use built-in tools (memo, useMemo, useCallback)
• Split code intelligently
• Virtualize long lists
• Measure the impact

Remember: Fast apps = Happy users! 🚀⚡