Although there are many apps available for OS X that can perform video encoding using the x264 codec, and therefore little reason to use a Windows-based encoder via a virtual machine, the x264 encoding process is extremely CPU-heavy, and serves as a good benchmark for measuring performance between VMs and native Windows installations.
Our x264 test is based on the popular Handbrake app and encodes a roughly 10-minute clip of the animated short Big Buck Bunny using the default “Apple TV 3” preset. The results are the average frames per second achieved during the encoding process, as reported by the Handbrake log file, with a higher number equalling faster performance.
There appears to be almost no disadvantage to using a virtual machine for single-pass x264 encoding with Handbrake, as Parallels 11 nearly matches native performance, clocking in at less than a single frame per second behind. Even Parallels 10 performs well, falling less than 5 frames per second behind Boot Camp.
These are encouraging results for users who need to use specialized encoding software that may only be available on Windows. You’re still not getting quite native performance, but it’s darn close.