Given my processor, I should have been able to process over 60 billion commands and read over 1.8 GB from my hard drive in the optimum theoretical 30 second XP startup time. My entire OS install plus the programs that run at startup aren't anywhere close to 1.8 GB.
With all due respect, have you considered the possibility that certain instructions execute more than once - put another way, loops?
I had a CS professor make the claim that merely dragging a scroll bar in MS WORD resulted in something like 750K machine level instructions. I have no idea if that is a verifiable fact but I think the idea that things that seems simple to humans involve a LOT of machine instructions is an idea that I'm comfortable with.
With all due respect, have you considered the possibility that certain instructions execute more than once - put another way, loops? Yes. I'm a programmer. But that's a LOT of horsepower being used just to start a program. OS X, with all its power and advanced GUI system, boots much faster than XP on the same hardware.