May as well link to the newer article on the subject. http://www.phoronix.com/scan.php?page=article&item=amd-aocc-optimizations&num=1
It's still not going to light the world on fire, but it's getting closer. That said, on the graphics front, using the RadeonSI/Gallium3D drivers will consume more CPU time than using Nvidia closed-source drivers.
Maybe things will get better around kernel 4.12 or 4.13? It took until 4.11 for some Ryzen optimizations, and support for the Realtek audio chip used in many AMD and Intel motherboards to finally arrive, so who knows what the future will hold?
Disclaimer: Before you call me an AMD fanboy, I couldn't care less between whether they or Nvidia win. They only things I'm keeping a sharp eye on from AMD, are the Threadripper and Epyc CPUs, since they might give me the best bang for my buck for the VM heavy workloads I run. I'm mildly interested in Vega, but not enough to lose any sleep over.