Weird problem in my PC

[saba17]

I play a lot of games and have some problems with some of them.When i try to play Among us for example or some other game it lags so bad,but when i put it on windowed mode everything goes normal.On fullscreen game is laggy but not all of the games i play.So what is the problem.please help and thank you

[Donny1]

I see your specs, the problem may be that your PC is just old and/or has slow parts?...