tedster - 7:35 pm on Nov 8, 2010 (gmt 0)
it depends on stuff that google doesnt know
since they know I am using GA they are probably trying to link up something?
Google mostly uses toolbar data from your visitors who have the toolbar installed, not GA. With a large enough sample, this gives them a good picture.
Google doesn't care what utilities you use to test your site - they care about how fast the pages load for visitors. How you accomplish that is up to you.
It's interesting to note that the key figure in researching and building the YSlow tool is Steve Souders. He was then hired by Google and worked on Google's Page Speed tool.