Real Impact

After analyzing 10,000+ websites, these optimizations consistently deliver the biggest performance gains:

Image Optimization— WebP format, lazy loading, responsive srcset. Average 40% size reduction.

Critical CSS— Inline above-the-fold CSS, defer rest. Eliminates render-blocking resource chain.

Resource Hints— `<link rel="preload">` for critical assets. `<link rel="preconnect">` for third-party origins.

JavaScript Deferral— `async` or `defer` attributes on non-critical scripts. Reduces main thread blocking.

Viewport Meta Tag— `<meta name="viewport">` prevents 300ms mobile rendering delay.

Measurement

Before optimizing, establish baseline metrics:

Core Web Vitals— LCP < 2.5s, FID < 100ms, CLS < 0.1

Lighthouse Score— Target 90+ Performance

Real User Monitoring— Track field CrUM data for actual load times