The mobile home page’s PageSpeed Insights score fell sharply since the previous weekly test. Something that changed in the last week has probably made the page slower.
What it means
The score fell by 15 points or more between two weekly tests, even if it’s still above the poor mark. Catching it now lets you fix it before real visitors’ Core Web Vitals, which cover 28 days, start to suffer.
What triggers it
The Lab performance service tests each mobile home page once a week with PageSpeed Insights and compares the score with the previous test. A fall of 15 points or more raises a Medium issue, and owners and admins get a “Critical issue alert” email the first time it’s found.
Common causes
- A new script, tracking tag, chat widget or plugin.
- New large images, videos or fonts on the home page.
- A theme update, or caching or a CDN being switched off.
How to fix it
- Check the timeline and your deploy history for what changed in the week before the drop.
- Run PageSpeed Insights on the home page and compare its biggest opportunities with what was added.
- Remove, defer or optimise the culprit, then retest.
When it clears
Each test is compared with the one before, so the issue goes at the next weekly test unless the score falls by 15 points again. A score that stays below 50 raises Slow in Google’s lab test instead.
After 7 days without the problem, the action drops off the board. If you marked it done and the problem is still detected 14 days later, it returns as “Fix didn’t work”.