Website Speed and SEO Impact: Performance and Rankings
Google has used site speed as a ranking signal since 2010. Core Web Vitals became ranking factors in 2021. Speed optimization has gone from "nice to have" to "must have."
Speed Impact on User Behavior
| Load Time | Bounce Rate Increase | Conversion Impact |
|---|---|---|
| 1 sec | Baseline | Best |
| 2 sec | +32% | -15% |
| 3 sec | +53% | -32% |
| 5 sec | +90% | -50% |
| 10 sec | +123% | -80% |
Core Web Vitals
LCP (Largest Contentful Paint) - Target: < 2.5s
Factors: Server response time (TTFB), resource loading, render-blocking resources, client-side rendering
INP (Interaction to Next Paint) - Target: < 200ms (Replaced FID in 2024)
Optimization: Reduce main thread blocking, optimize event handlers, avoid long JS tasks
CLS (Cumulative Layout Shift) - Target: < 0.1
Fix: Set dimensions on images/videos, avoid inserting ads above content, use font-display: swap
Optimization Strategies
Frontend
- Image optimization (WebP/AVIF, responsive images with srcset, lazy loading)
- Code minification (CSS/JS, tree shaking, code splitting)
- Caching (browser cache, Service Worker, HTTP cache validation)
- Resource hints (preload, preconnect)
Backend
- Upgrade PHP (8.x is 2-3x faster than 7.x)
- Enable OPcache
- Database optimization (slow queries, indexes, caching)
- CDN (static assets, HTTP/3, Brotli compression)
Monitoring Tools
- Google PageSpeed Insights: Core Web Vitals diagnosis
- Lighthouse: Comprehensive audit
- Chrome DevTools: Real-time analysis
- WebPageTest: Multi-location testing
- CrUX: Real user data
Summary
Measure first, optimize second. Fix easy wins first (images, cache, CDN), then tackle core issues (server response, JS efficiency). Speed optimization is ongoing maintenance.