I'm running 64-bit Windows 8.1 on a PC with 16 Gig RAM and 8 cores. I've noticed a lot of lag, e.g. all action momentarily stops and when it starts back up the game character quickly speeds across the screen. At other times when I join a multi-user session where there is a lot of action my computer will just freeze up permently. In that case I can use Ctrl+Alt+Del to get to Task Manager and kill the Diablo III process.
Any ideas what might cause that problem? Is it more likely to be my video card or the Blizzard servers? I don't see that problem anywhere else or in any other program. I'm considering buying a better video card, but no point wasting money for it if that's not the problem.