Alt Tabbing is definitely less stable than before - it does work sometimes, sometimes it crashed my pc and I had to do a hard boot (this happened with vanilla ETW, but was fixed in the first patch)... I only wanted to tab to task manager to see how the multi threading was going - There is evidence it's happening; there seems to be more activity on all the cores, and the main one is running about 66% rather than 99% like before (using a dual quad core) but there's zero effect to the frame rate...