What does Google PageSpeed measure?

[DanielMulderNL]

What does the PageSpeed tool actually measure?

Does it say that a webserver is fast or slow?

Thanks in advanced!

[DJ123]

In a lot of respects, it measure the efficiency of your site.  How well the code is optimized as well as your server in processing that code.  It is possible to have a poorly coded site which performs OK because you compensate for the bad code/bad layout by having more horsepower.  The server is definitely correlated to the pagespeed rank.  It's likened to a big differential equation with 100 factors all playing a role in the final output, but several of the items contributing to the majority of the output behavior.

Check out some of the documentation on it: https://developers.google.com/speed/docs/insights/about

The raw horsepower of the server is only going to get you so far.  You would be much better off designing a system with a small server which is super efficient, than spend tons of money on the top of the line server which is using all of its power to process inefficient code, assets, etc.

[DanielMulderNL]

I agree. I think it's primarily is a measure of the DOM efficiency of the code it self and how efficient it is when rendering by a browser. Server speed is a minimal part of it. All the caching in the world does not make it faster for to restart the rendering because of inline css. A faster responding server and download of the page only makes it possible to start faster with 90% of jobs that are relevant for PageSpeed but which are mostly handled by the browser alone?