Sometimes after zoning, I’ll get horrible FPS (visual stutter). The game remains in this state until I minimise it to the taskbar and then go to fullscreen again.
I’m playing in full screen more (1920×1200) on a 8GB, dual Xeon, 12-core Mac Pro running Windows 7 64 bit professional. The GPU is a GTX 670 by Nvidia but IIRC, it also happened with the ATI Radeon 5870.
It’s not game breaking since it can be fixed easily, but still, looks like a bug.