Maybe there are viruses in your PC. You can download an anti-virus software to check it. OR, it may be caused by too many junk softwares, you can get a related optimization software to clean them up.
Anti virus programs makes your pc slow. So make sure to know which one is suitable to your pc that doesn't give a slowdown on your pc performance. I have microsoft essentials and it is the best from all that I have tried.
Send your profile (CPU, memory, graphics card, etc.), and can help pin point cultprit. In the meantime, you should play with low graphics settings for best performance (yes, I know that you do not see) to play.
Comments
But virus problem in your system
so format your computer
If they don't work, reinstall your system.