Using EXA (and no other options in XOrg), I get a slightly higher peak in ppracer, with less fall off when more stuff is on screen. However Xorg now eats ~20% of CPU time so I'm going back to UXA.
Using EXA (and no other options in XOrg), I get a slightly higher peak in ppracer, with less fall off when more stuff is on screen. However Xorg now eats ~20% of CPU time so I'm going back to UXA.