Short answer
PageSpeed Insights has moved to a new Lighthouse version that changes how it simulates page load time. A page's lab score can therefore come out different even when nothing on the page changed. The update may affect JavaScript-heavy sites most. When comparing earlier and later tests, check the Lighthouse version and real-user field data.
Highlights
- PageSpeed Insights now uses Lighthouse 13.6.0; the change improves the simulation of first contentful paint and largest contentful paint.
- According to Barry Pollard of the Chrome team, scores will generally rise and JavaScript-heavy sites are more likely to be affected.
- Lab scores from before and after the update were not measured with the same simulation, so they should not be compared directly.
2 min readAuthor: UNIT Journal EditorEditor-in-chief: Uğur Deniz İlhan
As Search Engine Journal reports, PageSpeed Insights has moved to Lighthouse 13.6.0. Lighthouse is Google's page speed and quality auditing tool, and the performance score in PageSpeed Insights is based on the lab data it generates.
What changed?
Lighthouse loads a page at full speed and then estimates how long it would take on a slower connection; the part that makes that estimate is called Lantern. In the new version, Lantern decides whether a request blocks rendering using Chrome's own label for it. Also, when the largest content element is text, its paint time is estimated from the same requests and tasks as the first content. According to Barry Pollard of the Chrome team, this makes the first contentful paint (FCP) and largest contentful paint (LCP) estimates more accurate and generally raises scores.
If my score changed, did my site change?
Not necessarily. The same page can receive a different score because the test changed. Pollard says JavaScript-heavy sites are more likely to be affected. Field data collected from real users (CrUX) is a separate measurement and is not changed by this update.
What should businesses in Turkey do?
For a company running speed work, or receiving speed reports from its agency, the main risk is crediting a score rise to the wrong cause. If you manage your site's infrastructure on the web and e-commerce side, these steps help:
- Record the Lighthouse version shown next to the device information in each PageSpeed Insights report, and compare only reports taken with the same version.
- If your historical score charts show a jump on the update date, annotate it; do not report it as the result of an optimisation.
- Look at the last 28 days of field data (CrUX) together with the lab score, and show both to clients or management.
- If you run a JavaScript-heavy site, re-test after the update and work out the difference page by page.
Frequently asked
- Where do I find the Lighthouse version?
- In a PageSpeed Insights report, the Lighthouse version appears next to the emulated device. Check that two reports share the same version before comparing them.
Sources
- Search Engine Journal ·
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