Watching the the Ashes DX12 fiasco going on inspired me to try to see what kind of impact DX12 will have on my home machines. I have 2 nearly identical gaming machines except one has a GTX 780ti and the other has a r9 290x. I ran the DX 11 and DX 12 versions of the U4 Elemental Demo on each machine.
Each rig has a water cooled amd 8120 @4.4GHZ both have 8GB ram.
The tests were run at 1920x1080 full screen with no vsync.
My video renderer would crash if I used the entire DX 12 video recordings so I cut the video so that it would render. Later FPS would go up into the 70-75 fps range...