Are you talking about Google website optimizer? - Google website optimizer helps you in testing content changes (which you are planning to introduce in your website) - If you have an AdWords account, you can use Website Optimizer directly from the AdWords interface - It help you in testing your traffic’s response against different content http://www.google.com/intl/en/websiteoptimizer/ats.html
I think you should learn what is Google Optimizer. He is talking about Page Speed Optmizer. You should also mind that he is not asking about SEO.
I have used page speed optimizer without much success, if you wrote the code for the site you should be able to review it and omit and unnecessary code that causes pages to load slowly... I think this is what you're talking about -- if your question is unrelated to on-site SEO