pbuffer pixel formats

we’ve found that on quadro cards, performance of GL_POINTS is extremely sensitive to the pixel format that is chosen. For example, I found that I got a 10x speedup by choosing a pbuffer that did not have stencil bits (even though I was never enabling any stencil tests).

Does anyone know what pixel format attributes I need to look for or avoid to make sure I stay on the fast path on recent drivers for specific cards?