Page speed and Core Web Vitals
Follow how fast a page loads for visitors, next to whether it is up.
2 min readThis guide covers Premium features. Premium is in early access and cannot be bought yet.
Turn on page speed
- Edit an HTTP monitor whose address is a page people open in a browser.
- Open Advanced settings and enable Measure page speed and Core Web Vitals.
- Save the monitor. The first measurement follows its next successful check and appears on the monitor’s details page.
Read a measurement
Google PageSpeed Insights loads the page once a day as a phone would. The performance score from 0 to 100 and the blocking time come from that single test load, so they vary a little from run to run.
Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift are the Core Web Vitals. When enough Chrome visitors open the page, they are shown as the 75th percentile of real visits over 28 days; otherwise the test load’s values are shown, and Interaction to Next Paint, which needs real visitors, is left empty.
Good means up to 2.5 seconds for Largest Contentful Paint, 200 ms for Interaction to Next Paint, and 0.1 for Cumulative Layout Shift.
Plan and limits
Page speed requires Premium and an HTTP monitor. The monitored address is sent to Google, which makes the request itself: custom request headers are not sent, so a page behind a sign-in cannot be measured.
Measurements are shown, not alerted on. A failed measurement keeps the earlier ones and is retried within a few hours; pages that are down or paused are not measured. Changing the monitor’s address starts a new history.