While site speed is a new signal, it doesn't carry as much weight as the relevance of a page. Currently, fewer than 1% of search queries are affected by the site speed signal in our implementation and the signal for site speed only applies for visitors searching in English on Google.com at this point. We launched this change a few weeks back after rigorous testing. If you haven't seen much change to your site rankings, then this site speed change possibly did not impact your site.
We encourage you to start looking at your site's speed (the tools above provide a great starting point) — not only to improve your ranking in search engines, but also to improve everyone's experience on the Internet.
Posted by Amit Singhal, Google Fellow and Matt Cutts, Principal Engineer, Google Search Quality Team
