I was expecting something like this, but not in that scale. GCN proved hard to scale, the performance gains where in no relation to the increase of Compute Units at all. Mantle, and now DX12, manage to tap into that lost potential, which is why the framerates are growing so strong.
I am however surprised to see that NVidia actually regressed in performance. Maybe they where so optimized to the effects of DX 11 that DX 12 now proves more of an hindrance. On the other hand, it might just be (and probably is) a driver issue. In any case, I don't think that NVidia can increase nearly as much as AMD since their architecture had much less untapped potential to begin with.







