ReactPerformanceJavaScript
React Performance Optimization: Beyond useMemo and useCallback
January 8, 2024
12 min read
# React Performance Optimization: Beyond useMemo and useCallback
While `useMemo` and `useCallback` are well-known React performance optimization tools, there are many other techniques that can significantly improve your application's performance. Let's explore advanced strategies that go beyond the basics.
## Code Splitting with React.lazy
Dynamic imports and React.lazy allow you to split your code at the component level, reducing initial bundle size.
```jsx
const LazyComponent = React.lazy(() => import('./LazyComponent'));
function App() {
return (
);
}
```
## Virtualization for Large Lists
When rendering large lists, virtualization ensures only visible items are rendered in the DOM.
```jsx
import { FixedSizeList as List } from 'react-window';
const VirtualizedList = ({ items }) => (
itemCount={items.length}
itemSize={50}
>
{({ index, style }) => (
{items[index]}
)}
);
```
## React Compiler (Experimental)
The new React Compiler automatically optimizes your components, reducing the need for manual memoization.
```jsx
// The compiler automatically optimizes this
function ExpensiveComponent({ data, filter }) {
const filteredData = data.filter(item =>
item.name.includes(filter)
);
return (
- {item.name}
{filteredData.map(item => (
))}
);
}
```
## Concurrent Features
React 18's concurrent features like `startTransition` help prioritize urgent updates.
```jsx
import { startTransition } from 'react';
function SearchResults() {
const [query, setQuery] = useState('');
const [results, setResults] = useState([]);
const handleSearch = (value) => {
setQuery(value); // Urgent update
startTransition(() => {
setResults(searchData(value)); // Non-urgent update
});
};
return (
handleSearch(e.target.value)} />
);
}
```
## Bundle Analysis and Optimization
Regular bundle analysis helps identify optimization opportunities:
```bash
# Analyze your bundle
npx webpack-bundle-analyzer build/static/js/*.js
# Or with Next.js
npm install @next/bundle-analyzer
```
## Conclusion
Performance optimization is an ongoing process that requires understanding your application's specific bottlenecks. These advanced techniques, combined with proper measurement and monitoring, will help you build faster, more responsive React applications.
Remember: measure first, optimize second. Use React DevTools Profiler to identify actual performance issues before applying these optimizations.