Google's Core Web Vitals get a lot of attention, and a lot of hand-wringing. The scores can feel like a black box: you run a test, get a number, and it's not always obvious what to do next. Let's cut through it.
There are three metrics worth understanding, and each one maps to a real feeling a visitor has when they land on your site.
Largest Contentful Paint (LCP) - "has it loaded yet?"
LCP measures how long it takes for the biggest, most important thing on screen - usually a hero image or headline - to appear. If it's slow, your visitor is staring at a blank page wondering whether the site is broken.
The usual culprits are oversized images, slow hosting, and render-blocking code. The usual fixes:
- Serve images at the right size and in a modern format
- Preload the hero image so the browser fetches it early
- Put your site on fast, well-configured hosting
Interaction to Next Paint (INP) - "why isn't it responding?"
INP measures how quickly the page reacts when someone taps or clicks. Heavy JavaScript is almost always the cause of a poor score. Trimming unused scripts and breaking up long-running tasks keeps the interface feeling instant.
Cumulative Layout Shift (CLS) - "why did the button move?"
CLS measures visual stability. We've all tried to tap a link only for the page to jump and send us somewhere else. Reserving space for images and ads, and loading fonts carefully, keeps everything where it should be.
Chasing a perfect score is the wrong goal. Fixing the moments that frustrate real people is the right one.
Start with the experience, not the number
The best way to use Core Web Vitals is as a translation layer: each metric points to a specific way your site might be letting people down. Fix the experience, and the score follows.
If your numbers are in the red and you're not sure where to start, our Website Optimisation service can help - a focused performance pass often pays for itself. Get in touch and we'll take a look.