You might have the same issue that I have with my Lenovo W540 that just started recently as well. Check out my post here: Bizarre Graphics Framerate Issue
And video here: Solidworks Problem - YouTube
If you have a 3dconnexion mouse you could verify the same issue or not. My guess is Lenovo pushed some sort of driver update to it's laptops that is causing weird issues with the Quadro drivers.
It would be great to get some more visibility on this issue. I have a ticket about it in with Solidworks through our product vendor as well.
Hmm as of today, now even having the menu open does not solve the slowness issue...problems progress!