It may seem a bit odd to find a large section of a book about search engine optimization (SEO) dedicated to performance and speed, but to me, it makes sense. SEO is only partially about attracting visitors. The next step is to keep them on your site. Providing users with a good experience, by allowing them to browse fast through your site, is a crucial part of keeping them there. In addition, some research has shown that the time it takes to load a web site actually affects conversion rate, meaning that faster web sites sell more. You may have noticed yourself, if it takes too long to load a web site, you simply leave it and check the next site in the search engine results page (SERP). Even more important, Google has mentioned in one of its blog posts on the Webmaster Central site that site speed is considered one of the factors weighted for Google site ranking!