Prioritize Critical CSSThis rewriter will determine which css rules are actually needed to display the page, and will inline just that. Once it has done that, it will inline just that part of the css, and defer loading of the rest until after the page has been loaded.
Doing so greatly helps with speeding up page rendering. Normally, the browser will have to wait until all css is loaded before it can start rendering the page. With this filter however, the necessary css will be available almost immediately. This one can shave seconds on mobile browsers!