So I used to have a somewhat old computer and when I played GTA IV it ran fine. The graphics card I had was a Nvidia graphics card. Then I brought a bran new PC and it had all the updated hardware. The graphics card that computer had was an ATI graphics card. Whenever I try to play GTA IV on it, it really lags. I was wondering why that happens on my new PC and why it didn‘t happen on my old PC.