Help With The Laptop

hello idk if you reply to comments but i need serious instructions i am on msi gf63 thin 10uc (laptop) i have been facing a problem for a while now , when i was on windows 10 few days back i accidently installed some game from virus website and had to reinstall windows through windows update i was not able to use anything , so i updated to win 11 by win update only way to get out of virus, and after that i configured the win 11 i disabled defender and all , again i started facing same problem with the low performance idk why the frame in my games specially cs2 (counter strike 2 ) drops and stutters why is this happening i cant understand. Can you please help me how can i fix my problem