Waiting for gegl to be useful? but it turn out gonna be a long way to go. The concept behind it is damn good as utilising GPU potential power like nVidia or ATI will spare CPU some more cycles. It probably take a year more for complete usable gegl mode make its way in version 2.8.x. Others good news is this gegl will be a substantial foundation for CMYK, well actually for all other color modes and operation. Who knows it will be faster than Photoshop!
read more about gegl
download git version of GIMP 2.7 (AUS)