Why are they using Visual Studio at all then? Why not Textpad/Notepad++ or Emacs if they're so concerned about startup time? The only IDE that does come close to VS in functionality is Eclipse and that has a woefully slow startup time - never stopped any Java developer from touting that as the greatest IDE ever (it exceeds VS in many cases, IMO). Both of these IDEs, once they load, are extremely responsive considering the scale of the projects they are made to handle. JIT compilation occurs for chunks of code as you type code - that is dazzlingly fast for VS (and it's not just plain symbol-based lookup as used to happen in VS6 IntelliSense).
Incidentally, I don't think it was really features that made VS2010 slow
What do you think makes it slow during startup? According to me, it's sub-component/assembly/library load time during IDE startup and file parsing/symbol loading time during/after project-load.