Well, with UE3 based games on the Mac (Including the Batman: Arkham series and Bioshock Infinite to name a couple) performance is actually pretty good with the only features lacking being tessellation. That doesn’t mean it’s not a driver problem however, as UE4 may have just hit a performance impacting landmine in Apple’s drivers which can be the case often times. I just hope that whatever its, Epic can track it down.