web-performance-optimization

# Web Performance Optimization

## Overview

Implement performance optimization strategies including lazy loading, code splitting, caching, compression, and monitoring to improve Core Web Vitals and user experience.

## When to Use

- Slow page load times
- High Largest Contentful Paint (LCP)
- Large bundle sizes
- Frequent Cumulative Layout Shift (CLS)
- Mobile performance issues

## Code Splitting (React)

```javascript
import { lazy, Suspense } from 'react';
import { Routes, Route } from 'react-router-dom';

const Home = lazy(() => import('./pages/Home'));
const Dashboard = lazy(() => import('./pages/Dashboard'));
const Settings = lazy(() => import('./pages/Settings'));

function App() {
  return (
    <Suspense fallback={<Loading />}>
      <Routes>
        <Route path="/" element={<Home />} />
        <Route path="/dashboard" element={<Dashboard />} />
        <Route path="/settings" element={<Settings />} />
      </Routes>
    </Suspense>
  );
}
```

## Webpack Bundle Optimization

```javascript
// webpack.config.js
module.exports = {
  optimization: {
    splitChunks: {
      chunks: 'all',
      cacheGroups: {
        vendor: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendors',
          chunks: 'all'
        }
      }
    }
  }
};
```

## Image Optimization

```html
<picture>
  <source srcset="image.webp" type="image/webp">
  <source srcset="image.jpg" type="image/jpeg">
  <img
    src="image.jpg"
    srcset="image-400.jpg 400w, image-800.jpg 800w, image-1200.jpg 1200w"
    sizes="(max-width: 600px) 100vw, 50vw"
    loading="lazy"
    decoding="async"
    alt="Description"
  >
</picture>
```

## Service Worker Caching

```javascript
// sw.js
const CACHE_NAME = 'app-v1';
const ASSETS = ['/', '/index.html', '/main.js', '/styles.css'];

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then(cache => cache.addAll(ASSETS))
  );
});

self.addEventListener('fetch', (event) => {
  event.respondWith(