I just upgraded from 16.12.2 beta to 16.12.2 WHQL and the performance of Vulkan Doom 2016 dropped in half using my system.
My initial FPS were at ~110 fps using 16.12.2 and now using 16.12.2 WHQL dropped ~55fps.
So, it seems that the CPU utilization of my Core i5-2400 dropped also in half and that doesn't seem like a coincidence.
Did you change something internally in the Vulkan API because the version is exactly the same.
My system is Win 10 x64 - RX 470 - 16.12.2
I went back to 16.12.2 beta and everything is OK now, I'm back to my ~110 fps.
Please, fix that Vulkan issue ASAP or at least explain why the CPU usage of 4 core system went down to half (and so did the FPS)