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Performance

Core Web Vitals

CWV | Google Web Vitals

Portrait of Robert Klimant, co-founder of Roelu Studio
Robert KlimantCo-founder

What is Core Web Vitals?

Core Web Vitals are a set of three metrics Google uses to score real-world page performance: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for responsiveness, and Cumulative Layout Shift (CLS) for visual stability. Google's thresholds for a passing grade are LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1. Failing them hurts search rankings and conversion.

Why it matters

Google folded Core Web Vitals into search ranking because slow, janky pages bounce visitors. That part is well-known. The part most teams miss: CWV is measured on real Chrome users, not lab tests. Your fancy fiber connection in the office shows green. Your prospect on a mid-tier Android in a coffee shop sees red. We've audited Series B sites with award-winning design that fail every metric in the field. Pretty does not equal fast. If your CWV is in the red, you're paying a tax on every channel — SEO, paid, direct — and you probably can't see it in your analytics.

How it works

Google collects performance data from real Chrome visitors via the Chrome User Experience Report. Each visit contributes to a 28-day rolling average for LCP, INP, and CLS on each URL. You see your scores in Google Search Console, PageSpeed Insights, and tools like Vercel Speed Insights or PostHog. To pass, 75% of visits to a URL must hit the green threshold on all three metrics. Fixing them usually means image optimization, removing render-blocking JavaScript, reserving space for dynamic content, and trimming third-party marketing scripts. The work is rarely glamorous and almost never one-shot. The payoff is measurable in both organic rankings and downstream conversion rate.

Related terms

  • Largest Contentful Paint

    Performance

    The Core Web Vital that measures how long it takes for the biggest visible element on a page — usually the hero image or main headline — to finish loading in…

  • Interaction to Next Paint

    Performance

    The Core Web Vital that measures how quickly a page responds when a visitor clicks, taps, or types — Google's official replacement for the older First Input…

  • Cumulative Layout Shift

    Performance

    The Core Web Vital that measures how much a page jumps around visually as it loads — penalising sites where buttons, ads, or content shift unexpectedly under…

  • Page Speed

    Performance

    How quickly a web page loads and becomes usable for a visitor — measured in seconds and milliseconds, and treated by Google as a confirmed ranking signal…

  • Lighthouse Score

    Performance

    A 0–100 grade from Google's Lighthouse tool measuring a page's performance, accessibility, SEO, and best practices — used as a quick technical health check by…

  • PageSpeed Insights

    Performance

    Google's free tool for measuring how fast a page loads on mobile and desktop, combining real-user field data with lab tests and offering specific, actionable…

  • Technical SEO

    SEO/AEO/GEO

    The plumbing of SEO — making sure search engines can crawl, render, and index your site quickly and cleanly, so your content actually has a chance to rank…

  • First Contentful Paint

    Performance

    The performance metric that measures how long it takes for the first piece of content — any text, image, or graphic — to appear on the screen after a visitor…