Are you absolutely sure about that? Because, I gotta tell ya, from where I'm sitting, I can't see this distinction. The only instance I am aware of where FirePro and consumer GPU performance differed one little bit was in a bug report we got recently where something wasn't working on the FirePro card that worked just fine everywhere else, which is colouring my perception of the issue somewhat.
Here's another important difference in consumer and professional series video cards (from the nVidia Quadro wiki):
"Many Quardo cards use the same core as the game and action-oriented GeForce video cards by NVIDIA. Those cards that are identical to the desktop cards can be software modified to identify themselves as the equivalent Quadro cards and this allows optimized drivers intended for the Quadro cards to be installed on the system. While this may not offer all of the performance of the equivalent Quadro card, it can improve performance in certain applications, but may require installing the MAXtreme driver for comparable speed.
The performance difference comes in the firmware controlling the card. Given the importance of speed in a game, a system used for gaming can shut down textures, shading, or rendering after only approximating a final output—in order to keep the overall frame rate high. The algorithms on a CAD-oriented card tend to complete all rendering operations, even if that introduces delays or variations in the timing, prioritizing accuracy and rendering quality over speed."
This is another reason why you won't get the full benefits of OpenGL rendering on a consumer-level video card - the card's firmware prioritizes frame-rate over quality and will alter the image quality accordingly to keep frame rates high. It may be imperceptible in most cases and you wouldn't necessarily catch it during an intense battle in FSOpen, for example, but knowing it
would do that bothers me more than a momentary drop/fluctuation in frame rate (which I've never experienced on my PC - and perhaps others with more modern hardware).
