CSS and the critical path / Stoyan's phpied.com.
We’re going to be talking about performance on the front end like crazy for the next few years, there’s no escaping it. A lot has to do with mobile but just as much has to do with continuing to refine Web applications to be more performant, more like apps. Understanding how browsers work is essential to this process. This article focuses on the fact that [most] browsers delay page rendering until CSS is completely done transferring and suggests optimizing that path by omitting links to stylesheets completely.
While the solution isn’t elegant, it’s a solution, but unless you’re working with a single page Web app, you’re losing the ability to cache that (big) chunk of data on subsequent page requests.