-A pixmap is faster when drawing simple lines and polygons while an
-XImage is faster when Mesa has to do pixel-by-pixel rendering. If you
-need depth buffering the XImage will almost surely be faster.
+Using XImage is almost always faster than a Pixmap since it resides in
+the application's address space.
+When glXSwapBuffers() is called, XPutImage() or XShmPutImage() is used
+to transfer the XImage to the on-screen window.
+</p>
+<p>
+A Pixmap may be faster when doing remote rendering of a simple scene.
+Some OpenGL features will be very slow with a Pixmap (for example, blending
+will require a round-trip message for pixel readback.)
+</p>
+<p>