Website Speed Optimization: The Developer's Guide
Every 100ms of delay costs 1% in revenue. Amazon found every second costs $1.6 billion/year.
Core Web Vitals: LCP (loading) under 2.5s good, FID (interactivity) under 100ms good, CLS (visual stability) under 0.1 good, TTFB (server response) under 800ms good.
Image optimization (biggest impact): compress from 3MB JPEG to 150KB WebP (95% smaller). Techniques: convert to WebP/AVIF, compress with TinyPNG, lazy load, responsive srcset, serve appropriate sizes.
Code optimization: import only what you need (lodash 70KB to 4KB), minify and tree-shake, code splitting (500KB to 100KB initial). Caching: browser cache for static assets, server cache for pages/queries, CDN for edge locations.
Critical CSS: inline above-fold CSS, defer rest async (30-50% faster first paint). Quick wins: compress images (30 min), enable Gzip (5 min), add cache headers (10 min), defer non-critical JS (15 min), optimize fonts (10 min). We build fast from day one.