Not only is it a Mac thing, it's specifically the Aspyr Port to the Mac Thing. I play on a Mac, but in a Bootcamp Windows partition, so I'm playing the Windows/PC version, and the graphics and general performance are actually better post-Patch. I've been able to set the graphics options much higher than I could in the Mac version of the game, and have no noticeable slow down on the Large maps I used to play on with difficulty.