Of course, it's easy to clear that size with some big full-screen splash images, which are more and more common... it is kind of depressing. I really appreciate the work the Polymer team has done in creating paper components, and would love to see something closer to that for React as a base, most of the Paper/Component bases I've seen are still relatively heavy, with React-Bootstrap being one of the better ones.
It's not easy coming into something that's already in place, and harder to reign in the proliferation of modules that get added in.
The first point everyone should know about caching is to keep things as small as possible, and in fact, loading a tiny page over the network could even be faster than a locally cached but huge page that the browser needs to spend time parsing and rendering.
Definitely not in RFC 1123, though.