In 2021, Google started factoring page experience into rankings. That means how your site feels to use — not just what's on it — now affects where you show up in search results.
The three metrics that matter
LCP (Largest Contentful Paint) measures how long it takes for the main content to appear on screen. Under 2.5 seconds is good. Over 4 seconds is a problem. Slow image loading and heavy JavaScript are the usual culprits.
FID / INP (Interaction to Next Paint) measures how quickly your site responds when someone clicks a button or link. A laggy site — one that freezes or stutters — scores poorly here.
CLS (Cumulative Layout Shift) measures how much the page jumps around as it loads. You've experienced this: you go to click something and the page shifts, so you click the wrong thing. CLS penalises that.
Why this matters for sales, not just SEO
These aren't arbitrary metrics. A site that loads fast, responds instantly, and doesn't shift around converts better — because it's a better experience. Every 100ms improvement in load time has been shown to increase conversion rates by 1%.
How to check your scores
Go to pagespeed.web.dev and enter your URL. You'll get a score out of 100 for both mobile and desktop, with specific recommendations. Mobile almost always scores lower — and mobile is where most of your visitors are.
Most custom-built sites built with modern frameworks (like Next.js) pass Core Web Vitals by default. Most page builders don't.