The first thing you should do is to make sure that your game is running on DirectX12. Running the game in DX12 boosts your FPS in any game in the trilogy. Here are the steps you need to follow:

For this guide, we preferred going with GTA III as it is the most problematic title in the new trilogy, but it will work with all entries in the series.
  • Head to the install location of GTA III
  • Find LibertyCity.exe and right-click on the icon.
  • Create a shortcut of it and send it to your
...