You may gain some performance by doing the following...
Uninstall the gfx driver and run Driver Sweeper from safe mode. This one:
http://www.techspot.com/downloads/4266-driver-sweeper.html
Have DS remove any remnants of AMD, ATI, and Nvidia
graphic driver remnants it can find.
Install the latest driver for your card and OS.
http://www.geforce.com/drivers
Then run CCleaner and have it do the Clean and Registry portions both to clean up registry errors, junk files, and other resource wasting crap that can slow down your system:
https://www.piriform.com/ccleaner
You may have to run it more than one time if your system is badly corrupted.
Finally, disable as much as you can that is running in the background. Look in your Tray and in System Configuration/Startup. Everything running while you are trying to game is hogging resources and stealing clock cycles.