PageSpeed Insights Score Can Change Without Any Changes to a Site

[djbaxter]

Google: PageSpeed Insights Score Can Change Regardless of Changes to a Site
Search Engine Journal
Feb 6, 2019

Google’s John Mueller has advised that the PageSpeed Insights score can change without any changes being made to a website. .... Mueller says these scores are not physical measurements and may change over time whether or not the website itself has been changed. Ultimately, Mueller believes these tools should be used to find ways to improve a site for users. Achieving a particular PageSpeed score should not be seen as a final goal.

According to recent PageSpeed Insights release notes (Google doc link), there was a known bug in early February that led to lower scores.

“Between Friday Feb 1st and Monday Feb 4, the headless Chrome infrastructure used by PageSpeed Insights had a bug that reported uncompressed (post-gzip) sizes as if they were the compressed transfer sizes. This led to incorrect calculations of the performance metrics and ultimately a lower score.”

The bug was completely addressed as of Monday, February 4.

However, while mobile scores will return to their previous values, desktop scores are expected to remain lower.
As explained in the release notes, PageSpeed Insights now utilizes Lighthouse version 4.1.0 under the hood.

“Desktop scoring has been recalibrated to stay on par with the fast moving world of desktop browsing based on the most current data on global page speeds. You should expect desktop scores to be lower now than they had been.”

Read more...

 

[djbaxter]

Don't just rely on Google PageSpeed Insights metrics. Check Pingdom Tools and GTmetrix | Website Speed and Performance Optimization as well and follow their recommendations. Both of those show better speeds than the Google site. The new Google site at PageSpeed Insights is way out of whack when compared to other pagespeed services.

You will generally even get different results at Google's other PageSpeed site: Test Your Mobile Website Speed and Performance

 

[Rich Owings]

I use them all, and WebPageTest - Website Performance and Optimization Test too. Pingdom tends to give overly optimistic results. Almost all of these ESTIMATE page load time. Google Analytics shows real world user data and if a site is large enough, Page Speed Insights does too, using CrUX data.