jacob1:
Which version of OS X are you using?
I've never seen any unnatural slowness when testing it in my mac vm, but I have only used it minimally (just running it to make sure it runs ...)
Does it only happen after you leave it open for some amount of time? Or only after you do some certain thing?
I'm using El Capitan right now, But I had same issues when I was using public releases(playing since Mavericks)
It might do that if you are using Large Screen mode. Apparently there's some weird bug in that.