I have a pair of 6970s running in crossfire, a 2600k @4,4GHz and 16GB of RAM. In The Witcher 3, I get around 30fps (25-35) even with the 15.5 drivers (lowest settings 1080p). Before the new drivers, I played without crossfire and got about the same framerates which means that the update, except for allowing me to have crossfire enabled without stuttering, didn't improve performance with my 6970s. I don't think there is any other bottleneck since people with worse CPUs are getting better results. Also I'm frequently experiencing flickering on some surfaces such as grass or brick walls.
Is there anything I can do to improve my framerates? Will performance with 6970s improve in future drivers or do I need to buy something new?