The first DirectX 12 benchmarks have hit the web and confirm that the new new API offer ssignificant performance and CPU scaling benefit.
Guys at AnandTech.com tested a DirectX 12 version of Oxide's Star Swarm benchmark, using Nvidia and AMD GPUs. They used WDDM 2.0 drivers provided by Microsoft, Nvidia and AMD to enable DirectX 12 under Windows 10.
Of course, DirectX 12 is still a work in progress, so the results should just give you an idea of what we should expect to experience later this year.
According to results, Star Swarm's DirectX 12 and Mantle are offering about the same FPS (frames-per-second) on AMD's Radeon cards, with Mantle offering a slight performance edge.
Nvidia's GeForce GPUs also significant benefits from DirectX 12, though the improvement over DX11 is smaller, a behavior that should be attributed to the way Radeons handle Star Swarm's DX11 code path.
The article also covers power consumption and frame-time numbers.