There's a major downside to all of this complexity, however, because it degrades really poorly: I routinely see 30+ second page loads in Google Plus because they load a ton of code and you won't see anything until it completes 80-130 requests (warm/cold cache respectively) to load almost 5MB of resources! An ugly, non-interactive 1994-style simple HTML page would be far more useful to me at such times…

In practice, this happens to me multiple times a day on a normal connection and more frequently on congested or hotel crappy WiFi.