Yeah, a couple years ago (sorry, no citation handy) I wasn't too surprised to learn that a Windows desktop can run faster in a VM on Intel Mac hardware than directly on a similarly-priced PC.
IMO, the reason is all of the 3rd party fluff and poorly-written drivers that come with Windows PCs: Apple takes driver stability very seriously, and the drivers on a Windows VM are as vanilla (no fluff or features) as possible.