Google PageSpeed Insights, Optimizations improve but FCP and DCL Page Speeds do not change
Changes you make today to improve your Google PageSpeed insights report will take 30 days to reflect in the FCP and DCL scores. Even though Optimization scores improve immediately following changes to your website, the FCP and DCL are calculated using crowdsourced data over a 30 day period from the Google Chrome User Experience Report (crUX). This data is calculated in a rolling 30 days. For example, if your FCP speed after you made site changes is averaging 1.1 seconds, but before you made the changes it was averaging 11.1 seconds, the score will average the times together until 30 days have passed. Lets say 15 days from now you check your website, the FCP score will be about 5.1 seconds. Once 30 days have passed your FCP average will be 100% reflective of the changes you made 30 days before.
How long should I wait for the FCP and DCL scores to update?
Wait 30 days to re-assess your FCP and DCL score speeds in the Google PageSpeed Insights report.
Where do I go to test my webpages with Google PageSpeed?
Link to test your website on Google PageSpeed Insights: https://developers.google.com/speed/pagespeed/insights/
How can I contribute my browser usage to the Google User Experience Report?
You can contribute your web usage to the Google User Experience Report by enabling the “Automatically send usage statistics and crash reports to Google” option in Google Chrome. To enable, go to “Settings”, then click “Advanced”. Under “Privacy and security” section, toggle the option “Automatically send usage statistics and crash reports to Google” on, then restart your browser. Note, the statistics do not include any personal information but crash reports sent to Google User Experience Report at the time of a crash may contain web page URLs or personal information that was in the browser at the time of the crash.