We've just launched Site Performance, an experimental feature in Webmaster Tools that shows you information about the speed of your site and suggestions for making it faster.
This is a small step in our larger effort to make the web faster. Studies have repeatedly shown that speeding up your site leads to increased user retention and activity, higher revenue and lower costs. Towards the goal of making every webpage load as fast as flipping the pages of a magazine, we have provided articles on best practices, active discussion forums and many tools to diagnose and fix speed issues.
Now we bring data and statistics specifically applicable to your site. On Site Performance, you'll find how fast your pages load, how they've fared over time, how your site's load time compares to that of other sites, examples of specific pages and their actual page load times, and Page Speed suggestions that can help reduce user-perceived latency. Our goal is to bring you specific and actionable speed information backed by data, so stay tuned for more of this in the future.
The load time data is derived from aggregated information sent by users of your site who have installed the Google Toolbar and opted-in to its enhanced features. We only show the performance charts and tables when there's enough data, so not all of them may be shown if your site has little traffic. The data currently represents a global average; a specific user may experience your site faster or slower than the average depending on their location and network conditions.
This is a Labs product that is still in development. We hope you find it useful. Please let us know your feedback through the Webmaster Tools Forum.
Update on 12/04/2009: Our team just reconvened to provide you more information on this feature. Check out JohnMu's latest post on Site Performance!