Google offers an amazing tool that helps your website load quicker. It takes pages that are viewed most and helps the pages load quicker. Google PageSpeed service rewrites pages dynamically to lower the number of requests, PageSpeed will grab original content from your server and you site will be loaded via the Google CDN which is the same infrastructure that Google uses to load its websites worldwide. By using PageSpeed you reduce the number and size of resources to be fetched, PageSpeed service merges and compresses Javascript, CSS and image files. It then also offers paralyzed downloads (concurrent requests) of files when ever possible which means fewer HTTP requests. 

So your website is delivered faster to the browser.  Finally PageSpeed delivers the visible portion of your website first so if you page is very long and users have to scroll the top portion of the website will load first giving the impression of the entire website loading.  Today world having a website that loads quickly is important from not only a SEO perspective but also from a user experience perspective. If users are waiting and waiting for your site to load chances are they won’t stick around and wait for it to load and they will not be coming back.