GNOME 3.8 released

What is happening is called 'Wayland' and 'DRI 3.0'.

With X Windows as the display manager you have to have write out buffers multiple times, copy textures, do texture conversions, and do multiple rendering passes for things like 'server side decorations' if you want to have a composited desktop... for each time the display needs to be rendered, which is usually each screen refresh. You can't fix this without breaking X.

With the current drivers they have different sorts of video memory management schemes, which are not optimal from a security and performance perspective. Live and learn.

With Wayland and DRI 3 drivers all that copying/writing/converting and incrementing/deincrementing should be replaced by simply passing a file descriptor from the client application to the display server. So instead of shuffling around MBs of textures around you end up replacing it all with the copying of a couple bytes.