Google includes Site speed in search ranking algorithms

Google included site speed as a target for search ranking. An official blogpost on Using site speed in web search ranking posted by Amit Singhal & Matt Cutts had the following list of free tools that can be used to evaluate the speed of your website.

• Page Speed, an open source Firefox/Firebug add-on that evaluates the performance of web pages and gives suggestions for improvement.
• YSlow, a free tool from Yahoo! that suggests ways to improve website speed.
• WebPagetest shows a waterfall view of your pages' load performance plus an optimization checklist.
• In Webmaster Tools, Labs > Site Performance shows the speed of your website as experienced by users around the world.
• Many other tools on code.google.com/speed.