5 React Performance Hacks You're Not Using

Even experienced React developers often miss subtle optimizations that can dramatically improve app speed and user experience. While everyone knows about basic memoization and lazy loading, these five underrated techniques will help you eliminate wasted renders, reduce bundle bloat, and keep interactions buttery smooth—especially in complex applications.

1. Strategic Memoization Beyond Components

Most developers use React.memo for components and useMemo for expensive calculations, but few apply memoization thoroughly enough. Any function or derived value that gets recreated on each render—including event handlers, filtered lists, or formatted data—should be memoized if it's used in dependencies or passed to child components. This prevents unnecessary re-renders and keeps reference equality stable. The key is identifying hidden recalculations in your app that seem lightweight but add up across hundreds of renders.

2. Virtualization for Any List Over 100 Items

Rendering long lists without virtualization is one of the easiest ways to tank performance. Even if your dataset isn't massive, modern users expect 60 FPS scrolling. Libraries like react-window work by only rendering the items currently visible in the viewport, dynamically replacing content as users scroll. This approach slashes memory usage and DOM operations. Surprisingly, many teams wait until they hit performance issues to implement this—but the best practice is to virtualize by default for any list that could grow beyond a few dozen items.

3. Component-Level Code Splitting

Beyond lazy-loading entire routes, applying code splitting at the component level can dramatically reduce initial load times. Large modal dialogs, complex forms, and interactive data visualizations are perfect candidates for this technique. This approach ensures users only download the code they actually need, when they need it.

4. Custom Render Throttling

For high-frequency updates like animations, drag operations, or real-time data streams, implementing custom render throttling can prevent your UI from becoming unresponsive. By combining requestAnimationFrame with a custom scheduling mechanism, you can ensure your components only re-render at a rate that maintains smooth interactions.

5. Event Delegation Optimization

Creating event handlers for every item in a large list can consume significant memory. Instead, implement a single event handler at the parent level that uses event bubbling to handle interactions with child elements. This technique not only reduces memory consumption but also improves performance for lists that change frequently.