This is strange. When programmed correctly, the overhead of 3D on the CPU should be minimal and the GPU has nothing to do with networking. In SSFIV3D, it was made sense because the game only ran at 60fps in 2D and synchronizing a 60fps player against a 30fps one would be problematic considering they had to make it to release (but it's not impossible: the PC version supports different framerates for each player without problems).