Google opens up PageSpeed
Google has released Page Speed, an extension to Firebug for Firefox, as open source. Page Speed has been used internally by Google to analyse web site page performance from within the browser, using Google's Web Performance Best Practices to recommend changes that could be made to improve page performance.
Page Speed is available for Firefox on Linux, Mac OS X and Windows XP, and requires Firefox 3.0.4 and Firebug 1.3.3 or higher official non-beta versions. Developers interested in the source code should go to the Page Speed project page.