Ideally, in my opinion, when the browser makes a request for example.com/something the server should send a continuous stream of data. It could work something like this:

1) The browser sends the request along with a list of files it already has cached (maybe a special type of cache that never expires so the browser would know that it wouldn't need that file ever again).

2) Then web server sends the actual HTML that needs to be rendered, followed by whatever files the browser may need (css, js, images, etc). The browser would know where the HTML block starts and where other pieces begin, so from its point of view it's the same as if it requested those pieces. The difference is that the server anticipates these requests and sends them along all in one batch. The very first piece would be a list of files the server is sending, so the browser would know what to expect. At the end of the stream, if there are any more files that are needed that haven't been included in the main stream, the browser would just request them as usual.

Doing something like this would effectively render most page accesses to a single request, going from 10 or more requests to a single request would have quite a bit of an impact. For this to work though, both the browser and server would need to support such a feature...