Performance optimization is crucial for user experience and SEO. Slow sites lose visitors and rank lower in search. This article covers practical techniques you can apply today: code splitting, image optimization, lazy loading, and measuring what matters.
Measure before you optimize. Use Core Web Vitals (LCP, FID, CLS) and real-user monitoring to find the biggest bottlenecks. Often a few large images, render-blocking scripts, or heavy JavaScript on the main thread are the main culprits. Fix those first.
Images are usually the largest payload. Serve modern formats (WebP, AVIF), use responsive images with srcset, and size images to the display width. Lazy load below-the-fold images so the initial view loads quickly. Consider a CDN or image service for automatic optimization.
Split your JavaScript so users only download what they need for the current route. Use dynamic imports for heavy components or features that aren't needed on first paint. Keep the main bundle small so the page becomes interactive quickly.
Cache wisely. Set appropriate cache headers for static assets and use service workers for offline and repeat visits. For dynamic content, use short cache times or stale-while-revalidate so users get fresh data without waiting on every request.
Key Takeaways
- Use Core Web Vitals and RUM to find real bottlenecks before optimizing.
- Optimize images with modern formats, responsive sizing, and lazy loading.
- Code-split and lazy load to keep the main bundle and first load small.
- Use caching and CDNs so repeat visits and static assets are fast.
