You might have read several articles telling you to use Google's PageSpeed Insights to measure your website's performance, here's why it is bad advice:
- PageSpeed Insights does not measure the loading time of your pages.
- The PageSpeed grade you get on the result is not an indicator of page speed. It is a score based on some fixed assumptions.
- For example, it ignores the lazy loading of images which is a known technique to improve the visitor experience.
- In PageSpeed Insights, no website ever gets a perfect grade, so it is impossible to get 100. This means you are targeting between 0 and 80, not 100 as it appears to suggest.
- The score on Page Insights does not correlate to loading speed.