Follow these steps:

  1. Click on the Xquartz Icon and the Preference item
  2. Go to the Output Tab
  3. On the Colors: dropdown, select 256 Colors
  4. Close the Preferences window
  5. Restart XQuartz.
  6. This will have a huge effect on the drawing speed 10-14x better than it is
  7. This is a bug in Xquartz, not XPP