Alright, here's one of those dumb questions you seem very open to: Can we use this technique to (for example) reply with all of a page's dependencies upon the initial request? i.e. if a user goes to www.example.com/ and the server immediately replies with /, /favicon.ico, /styles.css, /script.js, /banner.png, etc? I imagine if it were possible, this would result in a massive reduction in latency...
Well, you can and you can't. See the problem is that you have no idea what the next request will be about! So if you're sending the same kind of request from the client you can respond with a payload in the mime type that is being expected. But for your usecase you could receive a request for /style.css and respond with /favicon.ico if a client decided to make the requests in an order that you did not anticipate.
If you get lucky it will work, but if you're unlucky then you'll be sending out the wrong payloads on all but the first request.
The only reason this trick worked for the webcam is because it knows ahead of time what kind of request will come (the request for the next frame). That's why it can anticipate.
Now that I think about it, one could use a small javascript library embedded in the index page to make a number of additional requests and interpret them as the correct types via data: URLs. That would be a lot of messy hacking to shave off a few hundred ms, but might be an interesting exercise to undertake...
