- Make HTML cacheable. Typically, most web pages are not cached because they contain small amounts of personalized information or other non-cacheable data. This rewriter separates the non-cacheable portions from the HTML and enables caching for the rest of the content on PageSpeed servers. When the page is loaded, PageSpeed servers send the cacheable parts immediately while non-cacheable parts are fetched from the origin server & patched into the browser later.
Early deployment of these techniques has shown significant improvements in user-perceived page load times. Below is a filmstrip view that compares the loading of pages on Power Line, a US-based political commentary website.