I've been playing on the 64b client the past couple of weeks and the performance is definitely not what I'd like; although it's not quite unplayable, in order to have a decent FPS I have to play on minimum settings, and even then it peaks around 30 and is usually around 20 or lower. That being said, I've never had the game crash, so stability issues seem to be fixed, which is good of course :) Would definitely love to be able to play on decent graphics settings or at least get better FPS at minimum. I'm on a mid-2015 15" MBP: 2.8 i7, 16 GB RAM, AMD Radeon R9 M370X