Slow code does matter. Especially in 3D. Although the video card is doing most of the work, your slower code is still the one pushing vertices and textures into

Slow code does matter. Especially in 3D. Although the video card is doing most of the work, your slower code is still the one pushing vertices and textures into the GPU and telling it where to draw them. If your code is slow enough, you won't be able to do that at a good refresh rate (remember, 60fps == 16.6ms per frame!)