Google let us know a while ago that the Google PageSpeed Insights tool has been modified so that it now also shows the effective loading time of your pages.
A welcome change, because there was a lot of confusion about this.
At Google, too, they apparently knew that the tool caused confusion among webmasters and that an adjustment was necessary. At least that is what I derive from the blog post about this adjustment:
PageSpeed Insights Provides information about how to adhere to a set of best practices. In the past, these recommendations were presented in the real world, which made it hard to understand when it was appropriate to apply these optimizations. Today, we’re announcing that PageSpeed Insights from the Chrome User Experience Report to make better recommendations for developers and the optimization score has been tuned to the real-world data.
The data about the speed comes from the so-called Chrome User Experience Report,
A project that Google managed to realize thanks to the data they collect through their own browser Google Chrome. The data is therefore from a large number of Google Chrome users worldwide who have given permission for this. Real-World data like Google puts it nicely in her blog post.
Google PageSpeed Insights now categorizes pages as: Fast, Medium, or Slow. Furthermore, the tool uses two different measurement methods: First Content Paint (FCP) and DOM Content Loaded (DCL). Your score is determined on the basis of the median value of these two measurements.
A big step forward for Google PageSpeed Insights. Now people with a fast site can immediately see that their site is doing well despite the fact that not all available optimization methods have been used.
The tool still continues to recommend that you do that and you can still take that with a grain of salt. Your visitors are really not awake from your Google PageSpeed Insights score, for them only the effective loading time of your page is important.