Page Speed is a Firefox addon who add a new functionality to Firebug enabling the user to evaluate and improve the performances of a web site. Although as improving perofrmances of a web site is no longer as critical as in the past with the evolution of new technologies, this has some advantages : Discover how to achieve this objectives with Page Speed. Page Speed needs Firebug to work because it add a new tab to the Firebug view. The installation is very simple. You just have to download the plugin from the official page and to install it like any other Firefox plugin. Then, you can launch Firebug and you should see a new tab "Page speed" : Page Speed You can now launch the analysis with the "Analyze Performance" button. Once the scan is complete (a few seconds normally), Page Speed will indicate what are the critical points of your web page. The advices are grouped into 5 categories : You can see the complete list of best practices on the site of Page Speed. Here are some example advices it can give to you : For fast all advices, the plugin say you how to solve the problem and improve the performances. To conclude, i would say that this plugin is essential for everybody who want to keep its web site faster. Links :