Major performance drop SolidWorks 2015

Other people have reported problems with recent driver updates for the Geforce series of cards (which aren't officially supported, but others have had luck reverting to older drivers). See this thread for details:

Re: Slow performance with GTX960m in SW2016

I hope this helps,

Jim

(wow,.. seems to be a popular issue lately... )

(repeated on this thread.... SolidWorks is SUDDENLY very slow today   )

What most likely happened,.. Windows Update auto installed the latest nvidia driver... unfortunately, there have been issues with nvidia drivers for the past 2 months.  (newer is not always better)

... as suggested.. look at your driver version and look over the past discussions using the search (top right maginfy glass)... for instance, use the words, "slow driver" .

IMHO.. reinstall your older video driver,.. if you know what it was?... or undo the last update using system "restore"....

,,if you don't want to do a system restore..    download one of the older nvidia drivers from about mid last year (~June 2016)

.. if for some reason.. the above is not the answer.. it could be some sort of corruption to the registry... search the forum.. "reset registry"

Good luck!