Speeding up websites is important — not just to site owners, but to all Internet users. Faster sites create happy users and we’ve seen in our internal studies that when a site responds slowly, visitors spend less time there. But faster sites don’t just improve user experience; recent data shows that improving site speed also reduces operating costs. Like us, our users place a lot of value in speed — that’s why we’ve decided to take site speed into account in our search rankings. We use a variety of sources to determine the speed of a site relative to other sites.
Just announced today over at Google Webmaster Central Blog – this is something you should already have been tweaking for user experience but knowing it will effect rankings in a small way (as one of over 200 factors) this should wake up some sleeping webmasters, SEO’s and designers.