robsc, Have you tried unchecking Use fast feedback in Window/Preferences/ OpenGL?

I don't think you're unsticking the program. Like any other program it will seem to freeze for it's system resources to catch up with given task. SU is a real-time renderer, recomputing all visible geometry with each change. With zooming, a lot of stuff has to repeatedly be redone.

Other options include tweaking your NVidia control panel settings. Make sure at least all settings that can be set to application control are set. Then have some 'fun' testing. And as always, update the