How does site speed affect conversion?
Users do not wait for a page to open. On a mobile connection, any page that takes more than three seconds loses a serious share of its visitors before they see any content. Speed hits ad costs, search rankings and conversion rate all at once.
What are Core Web Vitals?
The three metrics Google uses to measure user experience:
- LCP (Largest Contentful Paint): how long the largest element takes to appear — target under 2.5 s
- CLS (Cumulative Layout Shift): how much the page jumps while loading — target under 0.1
- INP (Interaction to Next Paint): how fast the page responds to interaction — target under 200 ms
The three legs of speed
Image optimisation (modern formats, correct dimensions, lazy loading), script clean-up (unused plugins and third-party code) and server response time (hosting quality, caching, database queries). On most sites, the gains are hiding in those three.
Quick wins
- Convert images to WebP/AVIF and serve them at their real size
- Self-host your fonts and use
font-display: swap - Remove unused plugins and scripts
- Defer third-party code (chat, maps, video)
- Use server-side caching and a CDN
Where do you start?
With measurement. Read PageSpeed Insights and the Core Web Vitals report in Search Console together — it is real user data (CrUX), not lab data, that should steer you. Then start cleaning from the largest file down; small gains add up to a real difference.
