Google PageSpeed and Core Web Vitals monitoring

A site's performance can change after every major modification. A new script, a heavier image, a template change or an extra plugin can make the score worse, even though the site still works correctly.

PageSpeed monitoring lets you observe these changes over time, instead of relying on a single measurement taken manually.

What is measured?

The results come from Google PageSpeed Insights and include, among other things, the core Core Web Vitals metrics, such as:

• LCP - the time needed to render the largest content element,
• CLS - the visual stability of the page,
• INP - the page's responsiveness to user interactions.

Results can be analysed separately for mobile devices and desktop computers.

Why is history more important than a single result?

A single measurement shows the state of the site at a specific moment. History, on the other hand, shows whether performance is improving, getting worse, or staying stable.

If the score drops noticeably after deploying a new version, you can line up the moment it worsened with the history of changes in the application.

Performance alerts

You can set a threshold at which a drop in the score should draw attention. This means you don't have to manually check PageSpeed after every deployment.

An alert doesn't tell you why the score got worse, though. It's a signal that it's worth checking recent changes, the page's assets and the results of a detailed PageSpeed analysis.

PageSpeed and uptime monitoring

These are two different kinds of monitoring. Uptime answers the question of whether the site is available. PageSpeed shows how well it performs from a performance perspective.

A site can therefore be available at all times while gradually becoming slower and slower.