React Performance Explained — Optimization Techniques

In this tutorial, you will learn about React Performance Explained. We cover key concepts, practical examples, and best practices to help you master this topic.

React performance optimization reduces unnecessary re-renders and improves perceived performance through memoization, virtualization, Code Splitting, and profiling techniques.

What You'll Learn

• How to identify performance bottlenecks
• How to use React.memo, useMemo, useCallback
• How to virtualize large lists
• How to code-split with Lazy Loading
• How to profile React components

Why It Matters

Without optimization, React apps can become sluggish with large datasets, frequent updates, or complex component trees. Profiling and optimization keep apps responsive.

import { useMemo, memo } from "react";

const ExpensiveList = memo(function ExpensiveList({ items, filter }) {
  const filtered = useMemo(
    () => items.filter(i => i.name.toLowerCase().includes(filter.toLowerCase())),
    [items, filter]
  );

  return (
    <ul>
      {filtered.map(item => (
        <li key={item.id}>{item.name}</li>
      ))}
    </ul>
  );
});

Expected output: The filtered list only recalculates when items or filter changes. The component only re-renders when its props change.