Not sure how I can explain this... first of all, I don't allow my computer to go to sleep at all. I just allow my HDDs to go to sleep if there is no activities for awhile. However, every time I come back to my computer at the login screen, the computer is so slow to have any response. This almost makes me think the Mac is stoped working. This slowness only lasts few mins and back to normal. Anyone has similar experience like I do? I have non-flashed GTX970 and SSD occupying 2 PCI-E slots. Not sure this makes any difference.