But there's not really a good reason why these features can not be processed in the background, e.g. in separate threads. Personally I don't care much about the 1GB file scenario, but I've mentioned before how "booting" AROS (AmigaOS reimplementation) hosted under Linux, straight into an Amiga editor like FrexxEd (which does have syntax highlighting for example) is faster than starting Emacs on my home machine.
More importantly, a lot of this functionality is down to simply not thinking about consequences. E.g. try starting a typical Emacs installation on a box that has a network but where the DNS setup is broken, and enjoy waiting for DNS lookups to time out before it starts... (I'm sure there's an easy fix; I'll admit to being lazy and not having looked for how to prevent it and rather "just" fix my DNS when it's happened)
All to often "nice to have" functionality ends up in the critical path of startup rather than lazily initialize in the background.