Core Web Vitals: web performance in service of your SEO

A slow site drives visitors away and hurts your SEO. Google measures part of the user experience through three metrics called Core Web Vitals. Understanding them helps prioritize the right technical work.

The three key metrics

LCP — perceived loading speed

Largest Contentful Paint measures the time before the main content (often a large image or heading) appears. Target: under 2.5 seconds. Unoptimized images and heavy scripts are the most common causes of a poor LCP.

INP — responsiveness to interactions

Interaction to Next Paint measures the delay between a user action (click, typing) and the page's visible response. A site that lags on click feels low quality, even if it loaded quickly.

CLS — visual stability

Cumulative Layout Shift measures unexpected movement of elements during loading. Ever clicked the wrong spot because a button "jumped"? That's poor CLS. You avoid it by reserving space for images and fonts.

Performance isn't just a score: it's real comfort for your visitors, and a signal to Google.

Where to start concretely

• Optimize and resize images (modern formats, appropriate dimensions).
• Limit non-essential third-party scripts that block rendering.
• Reserve space for elements to avoid layout shifts.
• Measure regularly with a tool like Lighthouse to track progress.

The good news: these optimizations are within reach of any well-built site. If you'd like a performance diagnosis of your current site, get in touch.