Whatever dude. 2Ghz\2GB RAM\256MB Video\160GB HD and there is NOTHING instantaneous about Parallels at all. It takes anywhere from 1-2 minutes to resume a session and another 2+ minutes to suspend it. This is with multiple images, several OS X installs, and I know how to tweak Windows with the best of them.
Sounds like you're not talking about Parallels starting up, but a virtual machine either resuming or starting up from scratch. For me WinXP starts in about 15 seconds on a 2.16Ghz 2GB RAM or about 2 minutes if resuming. But that has NOTHING to do with Cocoa, QT, Carbon or what not. The difference between those frameworks in speed is in milliseconds and would have nothing to do with the above. Those would have everything to do with file writing to disk.
I can say that when Parallels has its VM Flags set to VM Cache as the primary caching logic, its disk speed is near native, but OS X apps slow down dramatically. Change that to Mac OS X primary caching logic and the VM's disk access slows down noticeably, but not horribly.