Does Performance of you website matters to SERP -PageSpeed, Firebug

[speedo]

On Google Webmasters -> Labs-> Site Performance you can find how fast are your pages loading. You can even download plugin(i dont know if its made by google) to Firefox which is called Firebug and install PageSpeed.

When running an analyze with this PageSpeed it shows you page performance and gives you a rating from 0 to 100. Also it shows you what is that you need to do to solve these problems and how to do that. It links to a google help pages for info.
I hired programmers for my website who optimized all the pages on it and all of them have ratings now not lower than 93 out of 100, some even 97 and 98. I tried to test google pages, even google doesn't show that good results.

So I`m curious if anybody know anything about it and if had any experience before.
Also I will update you guy if anything will change in my SERP`s after those changes.