Importance of page load time for SEO
SEO experts are expecting Google to give more importance to page load times in search ranking. This simply means faster site will have more weight in search results. Google is already measuring average page load time, through its toolbar. Google started measuring page load time in early August 09 (at least for sites I monitor).
Before this webmasters and owners just had to worry about crawler speed now they have an other area to cover. Managing good crawler speed is relatively easy to gain, as it only includes delivery of html. On other hand page load includes delivery of html, images, css, js etc and order in which these are provided.
There is a lot of stuff available to improve site performance on server and on client browser in Web Performance Optimization.