I think that even using more than one bit per RGB channel isn't hard. For example, 0 -64-128-192-255 for each RGB would increase the speed for 15 times. The 1-2kbps would become 30kbps, a modem from few years ago.

When using the real webcam (and not just passing files around), just one frame for calibration and no auto-white balance should be enough.