Thought this viewtopic.php?p=54073#p54073 (and the immediately prior post to that), might be worthy of a cross link.
I visit yahoo finance pages typically daily and with two X's running that quite heavy page can be sluggish but with just a single X and framebuffer style GUI its more zippy (quick).
Measuring the exact same instances and using glxgears I see a 250 fps -> 310 fps difference/improvement (24% faster).