Reason why OpenGL is so much faster than Direct3D?

[Gonad the Barbarian]

Serious Sam 1&2, UT, and now the UT2K3 demo all run better in OpenGL than in D3D. I assumed it was because OpenGL rendering in those games was getting priority attention from the developers. But since UT2K3 defaults to D3D with no way of changing it without manually editing the .ini, I have to assume it was given priority over OpenGL this time. But running in OpenGL looks just as good and is about 20% faster. So is D3D just slower by nature? Or are Nvidia's D3D drivers not as speedy as they should be?

 

[Rand]

FWIW, according to the readme, UT2003 offers better performance and visual quality with the D3D renderer.

 

[kylebisme]

actualy all the prety shadows and fancy lighting go away with opengl, but it is faster despite what the readme says. granted, that proably mostly because it doesnt have the shadows or lighting going.

 

[BFG10K]

OpenGL has traditionally run better because it has received more developer support. That's not to say that it's not possible to get Direct3D games that run great (Command And Conquer Renegade is a good example).

In the case of UT2K3 I'm assuming that the reduced eye candy is the contributing factor to the performance delta.