Website Speed Optimization – Core Web Vitals Guide

Why is site speed important?

• Loading over 2 seconds → 50% users leave.
• Google Core Web Vitals affects SEO ranking.
• E-commerce conversions directly tied to speed.
• Mobile users (70%+) leave slow sites quickly.

What is Core Web Vitals?

LCP (Largest Contentful Paint)

Largest element load time. Target: ≤ 2.5 seconds.

FID / INP (Interactivity)

Site responds to user interaction time. Target: ≤ 200ms.

CLS (Cumulative Layout Shift)

Visual stability – elements don't shift during load. Target: ≤ 0.1.

How to increase speed

1. Image optimisation

• Use WebP/AVIF formats.
• Lazy loading (only on-screen images load).
• Responsive images (matched to device size).
• Use CDN (Cloudflare).

2. Server and hosting

• Choose fast hosting (modern VPS, cloud).
• Enable HTTP/2 or HTTP/3.
• Gzip / Brotli compression.
• Server-side rendering (SSR) Next.js or similar.

3. CSS and JavaScript optimisation

• Minify (compress).
• Code splitting – only needed code loads.
• Tree shaking – remove unused code.
• Inline critical CSS – speeds up first paint.

4. Caching

• Configure browser cache headers properly.
• CDN cache (Cloudflare).
• Server-side cache (Redis).

5. Third-party scripts

• Google Analytics, ad pixels – weaken performance.
• Use async / defer attributes.
• Lazy load third-party widgets.

Speed measurement tools

• PageSpeed Insights: Google's official tool.
• WebPageTest: detailed analysis.
• Lighthouse: in Chrome DevTools.
• GTmetrix: alternative tool.

Speed optimisation with ONE Studio

Audit + optimisation project: AZN 2,500-12,000. Our client sites typically achieve 90+ Core Web Vitals scores.