Do Core Web Vitals matter for AI readiness?
Performance is about how fast and how steadily your page loads for a person in a real browser: the Core Web Vitals, plus the weight of what the page downloads. It matters to a machine because a slow server and a heavy document delay every fetch, a crawler's included. Most of what the vitals measure, though, happens in a browser that AI crawlers never open, so mostly they describe the people who click through from an answer. Below are the 4 checks in this course, what each one looks for, and what good looks like. We measure one page load on a simulated phone, plus real Chrome users' numbers where Google has enough of them; we can't see how any one AI company's fetcher experiences your server.
Measured live through Google PageSpeed on every single-page scan and on the homepage of a site scan, and shown on their own dial, never in your headline score.
The checks in this course
4 checksLargest Contentful Paint (LCP)
LCP marks when the main content finishes appearing in a real browser. It's one of the three Core Web Vitals, and it describes the person who lands on your page rather than the crawler that read it: AI crawlers fetch your HTML and don't wait for it to paint.
What good looks like LCP under 2.5s.
Cumulative Layout Shift (CLS)
CLS measures how much the layout jumps around as the page loads. Shifting content makes people mis-tap and erodes trust; a crawler reading your HTML never sees it, so this one is about your visitors.
What good looks like CLS under 0.1.
Interaction to Next Paint (INP)
INP measures how quickly the page responds to taps and clicks — the Core Web Vital for responsiveness. Only real visitors can produce it, so it appears when Chrome has enough real visits to report.
What good looks like INP under 200ms.
Page weight and render-blocking
Page weight is the total size of everything the page downloads, and render-blocking files are the ones a browser has to fetch before it can show anything. A heavy page is slow on phones and slow connections, for people and for machines alike. Measured in the lab run and graded by Lighthouse's own audit scores.
What good looks like A lean total transfer size and no meaningful render-blocking savings left on the table.
Words you'll meet here
How does your page read to a machine?
A free scan of any page measures these live, alongside everything else — no signup. The performance numbers take a little longer than the rest.
Rather have it handled? No pitch, just a plain-English chat.
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