CC 2014 Liquify on my Windows 7 workstation with a Nvidia Quadro 4000 and Wacom Intuos5 tablets seem to work quite well except when a small brush tip is used. Small brush tip size seems to have lag problems. Large brush tips work well in Liquify. However large tips wet mixers brushes have some lag. I have the GPU advance option set to advance. There are problems with gradients banding with this setting basic works better there but basic mode cause other problems. Adobe stated years ago they were aware of the banding problem and would look at it.
CC 2014 has not crashed on me yet....