I today upgraded my WIN8 64bit system (3770K, Geforce670, 32GB) to latest nvidia card driver release 314.07 and found that blender immediately reacted very slowly in the interface - I saw delays in menu openings, modelling and especially in the numpad functions in ortho view (if you are in ortho mode and hit e.g. 7 for top view, what seems to happen is that blender switches to top view perspective first and puts it into ortho view in a second step). This second step was significantly delayed or skipped. This resulted in a very funny interface behaviour.
I reverted back to the 310.90 driver release for nVidia cards and blender behaves normal again. I checked this and the problem was similar with blender versions 2.65.5 (a 52 build and a 54 build from graphicall.org) and also with newest 2.66.0 from blender.org.
So my advise is to stay away from 314.07 for now and to disable autoupdates. Can others please check whether this is specific to WIN8 or happens at WIN7 as well (32bit and 64bit drivers respectively)?
Thank you for all reporting back into this thread whether this is a singular issue. There seemed to be other problems here:
and Blender programmers said this is a support and not a coding issue.