Lag in Sketching.

Hi There, I am having trouble with Lag when I am doing a sketch, or when I open the properties tab in the top task bar, and when I go to close it, it can take a minute to fully close, the same when I am putting dimensions in a sketch, I get Lag and cannot do anything until it catches up.

I am running Windows 7 Ultimate 64 bit, with 16 gb Ram, Quardo K4000 video card, i7 -2600 CPU@3.40GHz .

Thanks for any help that I can get to fix this problem.

Peter Smith