Website speed: why it matters for SEO

13 August 2026

The metrics that matter

• LCP (Largest Contentful Paint): when the main content appears. Target under 2.5 seconds.
• INP (Interaction to Next Paint): how quickly the page reacts to taps and clicks. Target under 200ms. This replaced FID as the interaction vital.
• CLS (Cumulative Layout Shift): how much the page jumps. Target under 0.1.

Page load “under 2 seconds” is a user-level goal we still use in briefs. Lighthouse 90+ on mobile is the lab check. Field data in Search Console is the exam that counts.

Why Google and buyers care

Slow pages waste crawl budget and raise bounce. On a phone in Zone 2, a 6-second LCP feels like the site is broken. Competitors who ship lighter HTML win the enquiry even if their brand is weaker. Speed will not replace relevance — a fast site about the wrong topic still will not rank — but a slow site about the right topic leaks both rankings and forms.

Fixes that move Lighthouse without gimmicks

1. Hero image: sized, compressed WebP, width and height set to prevent CLS.
2. Fonts: two families, display=swap, preconnect to Google Fonts or self-host.
3. CSS: one file, critical layout in the first kilobytes, no unused frameworks.
4. JavaScript: defer, no jQuery, no tag-manager soup on first paint.
5. Lazy-load below-the-fold images. Never lazy-load the LCP image.
6. CDN (Cloudflare) in front of origin. London PoP helps UK users.
7. Hosting that is not a £2 overloaded shared box running 30 plugins.

These are standard on our development builds and part of technical SEO audits. More design-side discipline is in best practices.

How to measure

Use PageSpeed Insights for a URL, WebPageTest for a filmstrip, and the Chrome Web Vitals extension while you click around. Test on “mobile” every time. A 99 desktop score with a 41 mobile score is a fail.

If your current site is stuck, a redesign is sometimes cheaper than fighting a page builder. Talk to us via the enquiry form.