Faster sites convert better and rank higher. Core Web Vitals measure real-world UX: LCP (load), CLS (layout shift), and INP (interaction).
1) Optimize images (biggest win)
- Serve modern formats (AVIF/WEBP) with responsive sizes.
- Lazy-load below-the-fold images.
- Compress aggressively while keeping clarity.
Checklist
- 'srcset' + sizes set
- Lazy-load non-critical images
- Use AVIF/WEBP where supported
2) CSS & JS strategy
- Inline critical CSS; defer the rest.
- Split vendor code; load non-critical scripts 'defer'/'async'.
- Remove unused CSS/JS and third-party bloat.
Checklist
- Critical CSS extracted
- Defer/async non-critical JS
- Audit third-party scripts quarterly
3) Caching & delivery
- Use a CDN; enable compression (Brotli) and HTTP/2 or HTTP/3.
- Cache HTML for anonymous users where possible.
- Preload key assets (fonts, hero image) responsibly.
4) Layout stability (CLS)
- Always reserve space for images/ads/embeds using width/height or aspect-ratio.
- Avoid late-loading fonts that shift text—use 'font-display: swap;'.
5) Interaction responsiveness (INP)
- Keep main thread light (avoid heavy synchronous tasks).
- Debounce input handlers; use web workers for expensive work.
Verify & iterate
Run PageSpeed Insights and Lighthouse regularly. Fix the worst offenders first. Re-test after each change.
Bottom line: Aim for a fast, stable, interactive experience—your users (and your conversion rate) will thank you.
