I would say there have been improvements. I can play for hours now on the Mac side without any weird artifacts or screen corruption. Over all fps seems to be pretty steady, even in dungeons with lots of spell effects, it still feels crisp and responsive. I seem to get better fps windowed but full screen is so lovely i don't mind taking a bit of a hit there. I play on a 27 inch iMac.

I am excited that its going to be back on sale this month!