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Core Web Vitals (LCP, INP, CLS)

Core Web Vitals are three measurements Google uses to describe how a page feels to the people visiting it: how fast the main content shows up, how quickly the page reacts when someone taps or clicks, and whether things jump around while it loads.

Why it matters

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The three metrics cover what visitors notice most: waiting, a page that doesn’t react, and a button that moves away at the moment they tap it. Google rates each of them as Good, Needs improvement or Poor, using real Chrome visits rather than a test. A page passes the Core Web Vitals assessment when all three are Good for at least 75% of visits.

Google also recommends good Core Web Vitals for success in Search. Together with other aspects of page experience, they’re part of what its ranking systems reward.

What influences it

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Each metric has its own causes, and the pages linked above go through them. In short:

Server and Cache: A slow server response delays everything, so LCP suffers first. On WordPress, a missing page cache is the most common reason.

Browser: Large images, render-blocking stylesheets and scripts push back LCP. Heavy JavaScript from themes, page builders and plugins makes INP worse. Images, ads and embeds without reserved space cause layout shifts.

WordPress: Cookie notices, sliders, chat widgets and ad slots often add work or move content after the page has appeared.

In Permo

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Permo marks LCP, INP and CLS with a CWV label. The official assessment uses real-user data only. The lab test measures LCP and CLS as well, but it never taps or clicks, so it can’t measure INP; Total Blocking Time gives a hint about responsiveness instead.

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Sources