PageSpeed Insights, Done Properly
Google's free tool that reports real-user Core Web Vitals from the Chrome UX Report alongside a Lighthouse lab test for a given URL.
Marcus Adeyemi
The key figures
- Field section
- real-user data from the Chrome UX Report
- Lab section
- a Lighthouse test run on Google's servers
- Assessment
- Core Web Vitals pass or fail based on the 75th percentile
- Levels
- results for the URL and for the whole origin
Why this is worth getting right
It is the most common first check of a page's performance, and reading it correctly means separating the field results from the lab diagnostics.
Do this, not that
Do
- Read the field data before the lab score
- Use the diagnostics to find specific opportunities
- Test several representative templates, not only the homepage
- Re-run lab tests more than once
- Record results before and after changes
Don’t
- Treating the performance score as the Core Web Vitals result
- Testing only the homepage
- Reacting to one lab run
- Ignoring the origin-level data
When to bring in help
Our advice Bring in help when PageSpeed Insights reports failing Core Web Vitals and the cause is not clear from the diagnostics.
Where this comes from
- Google for Developers — About PageSpeed Insights
- web.dev — Core Web Vitals
The figures and practices above come from the sources listed.
Working on something like this?
We take on Performance & Accessibility work for teams who want it done once, properly. Tell us what you are building and we will tell you honestly whether we are the right studio for it. Start a project.
Where to go next
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
