You are correct that "enabling hibernation" should have no effect on Windows 7 startup or shutdown performance, though I have no idea how quickly Windows 7 can enter and wake from hibernation with no user sessions open. While this would be easy enough to test, I also don't care: Windows Server 2008 R2 cold boots to a usable desktop in twelve seconds on my machine, which should be fast enough for anyone.

If you hibernate in Windows 7, and then boot, it takes approximately the same period of time as "booting" in Windows 8 (with "Fast Startup" enabled).

I have tried it. I do know. In fact if you measure it "to desktop" then Windows 7 full hibernation beats Windows 8's fast startup, because Windows 7 caches user programs in additional to Microsoft's side (i.e. registry, services, kernel, etc).

Interesting. Now allocate 20GB of non-paged pool and try again.

That's a fairly obscure scenario. Plus, if that allocation was within a service or driver then both Windows 7 hibernation and Windows 8 Fast Startup would have to page it to the Hibernation file.

"Interesting" was my main point; the non-paged pool comment was mostly kidding. Interesting in that it could indicate a "de-hibernation" process that's nothing like the "inverse of hibernation" one might naively think it should be: while hibernation must write 100% of allocated physical RAM to disk, "de-hibernation" need only restore non-paged pool plus whatever else is necessary to reinitialize the virtual memory subsystem (including whatever drivers are necessary to support it, of course). This done, the balance of the hibernation file could effectively be treated as a page file.