PC graphics card with fast framebuffer readback

Hi,
I’d like to get a PC graphics card that can read the framebuffer back quickly. I don’t mind if it’s a professional card CAD card, either. It is my understanding that most PC graphics card manufacturers do not optimize the glpixelread commands, and as such, reading information back from the framebuffer is done very slowly because of the essentially 1 way rendering pipline used for games.