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PerformanceTypical severity: Low

Core Web Vitals Scanner

Measures mobile performance via PageSpeed (LCP, CLS, TBT) and flags metrics in the poor range.

What it checks

This scanner measures your site's mobile performance using PageSpeed, looking at Core Web Vitals like LCP, CLS and TBT. It flags the metrics that fall into the poor range, meaning those that create a slow or unstable experience for the user.

Why it matters

A slow site, or one that shifts around while loading, frustrates visitors and makes many leave before seeing your content. On top of that, Google uses these metrics as a ranking factor, so poor performance also hurts you in search.

How to fix it

Optimize your images, load only the JavaScript you need, and reserve space for elements so the page doesn't jump while loading. Tools like PageSpeed give you concrete recommendations per metric, so start with the one flagged as worst.

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