Relevancy is the most important. If you have two sites that are equally relevant same back links, everything else is the same, you’d probably prefer the one that’s a little bit faster. So Page Speed can, in theory, be an interesting idea to try out for a factoring and scoring different websites.
We have over 200 signals in our scoring to try to return the most relevant, the most useful, and the most accurate search results that we can find. So, that’s not going to change. Our philosophy will always try to be “Try to return the best page to users.” Try to give them information about what they typed in.
But if you can speed your site up, it’s really good for users as well as, potentially down the road, being good for search engines. So, it’s something that people within Google have thought about. Wouldn’t it be great if we could find a way where sites that are especially fast, or sites that are really, really, really bad experience for users. It would be only one of over 200 different factors, but still could be a small factor in saying, “Yeah, you know what? This person’s worked hard to deliver a really good user experience in addition to be in relevant.” So, let’s show that to users.
by Matt Cutts - Google's Head of Search Quality Team