Run Safe Mode on your PC. Win 10:
Open the Start menu and click or tap on the Power button. Then, while keeping the Shift key pressed, click or tap on Restart.
Use a Good free anti-malware software and scan your PC. (Malwarebytes)
Low Frame Rate (FPS) Troubleshooting
Keep your video drivers up to date.
Change in-game settings.
Disable or remove potentially unwanted programs.
Reset your graphics card software.
Repair corrupt game files.
Set Windows to best performance.
Minimize effects of heat.