Google measures how real visitors experience your pages. Three numbers, the Core Web Vitals, sum it up — and they influence both rankings and conversions.
The three metrics
- LCP (Largest Contentful Paint) — how quickly the main content appears. Aim for under 2.5 seconds.
- INP (Interaction to Next Paint) — how fast the page reacts to taps and clicks. Aim for under 200 ms.
- CLS (Cumulative Layout Shift) — how much the layout jumps while loading. Aim for under 0.1.
Fixes with the biggest impact
Images: serve WebP or AVIF in the right size, lazy-load everything below the fold and give the hero image a high fetch priority.
JavaScript: ship less of it. Split bundles, drop unused libraries and avoid long tasks that block the main thread.
Fonts and layout: self-host fonts, reserve space for images and embeds, and never insert banners above existing content.
Measure, then improve
Lab tools like Lighthouse are a good start, but field data from real users is what counts. We check both before and after every release, so performance never quietly slips.