Non-Apple hardware does not differ in any meaningful way from Apple hardware. The performance of anything in OSX is perfectly tuned for any generic desktop computer. It also supports most hardware straight from the box.
Any generic desktop computer with the same hardware. It sounds like they're using Apple's image pipeline, which I imagine would be designed around the specific graphics hardware in the Mac Pro. Sure it could work on other hardware, but when you know exactly the hardware you're running on you can do a lot of low-level optimizations you couldn't otherwise do.