A lot of things can cause performance issues in the gaming industry. There is an unimaginable amount to Hardware, Software & Driver combinations. Take into account every piece of hardware or software has been setup and configured in an unknown way by the user.

The Operating system its self is always updating and changing. We could also have unwanted malware on the computer causing all kinds of problems and background changes.

Basically, the life of a PC Gamer is not easy. Some things to think about:

Update ALL drivers
Update your drivers, graphics and audio drivers first. Don’t forget audio can also mean updating your USB headset software and drivers. I.e. my Corsair 7.1 Headset is the best headset iv ever had, but the software/drivers suck. All check if any important motherboard drivers need updating. The GPU and Audio is not the only parts of a high-performance PC
Turn Off V-Sync (If this does not fix the problem, turn it back on.)
Try turning off V-Sync (or ‘Enhanced Sync’ on newer AMD Cards).

V-Sync attempts to eliminate screen-tearing by limiting the FPS(frames per second) to match your monitors Hz(Refresh Rate).

Example. If your monitor has a 60Hz refresh rate it can’t physically show more than 60 FPS. V-Sync will attempt to limit your GPU output to 60 FPS.

Problem. This option can sometimes  cause unforeseen graphical problems. Usually this can be turned off in the settings of the game under the video options. This can also be turned off in the NVIDA Control Panel.

Wondering what the refresh rate of your monitor is? go to Display settings > Advanced Display Settings. Rembner your looking for Hz.

Close unnecessary background processes and programs causing issues.
Try a free program called JetBoost, remember to configure it first by clicking the Customise button. Tick everything you don’t need, be careful only to select things that you know, many background programs and processes are needed by windows or your hardware.  

Once you have customised it, Click Boost

Remember, this is only a temporary fix. If this indeed fixes your issue, you need to isolate the actual program that’s causing the issue. Trial and error turning things back on one at a time.