Nvidia GeForce GTX 680MX settings

since a while I have the problem that my rhino viewport freezes for some seconds (specially perspective view), even without much geometry in my scene. I already updated my graphic card driver, but didn´t helped. maybe it is something wrong with my GeForce Settings? Does someone has an idea?
thanks in advance

software versions:
rhino 5 64 bit latest update
windows 7 professional

computer hardware:
intel core i7 3770 cpu @ 3.4 GHz
Nvidia GeForce GTX 680MX 4GB

Any plug-ins that you recently installed that are possibly doing this?

Try disabling all third party plug-ins and enable them one-by-one to identify the offending one. (Hint: make sure they are actually loaded by executing at least one command of the plug-in)

I switched off all plugins and restarted rhino, but still I have the same problem.