Why is there a difference in performance when I set the graphics options to use OpenGL vs. DirectX?
90% of 3D games out there are based on DirectX. It’s a well known fact that OpenGL suffers on certain graphics cards, especially ATI. NVIDIA on the other hand has a more robust OpenGL implementation and the divergence between the APIs is not that severe. However, even on NVIDIA OpenGL is always somewhat slower than Direct3D (DirectX).
