Hey guys, I’m looking into this issue. Are you all using 900-series GPUs?
It sounds like 's issue is different, but if the rest of you are seeing crippling performance issues on such powerful computers, something’s definitely going wrong. I’ll get back to you when I have more information - let me know if you find out anything.
Edit: As a side note, can you try removing the light source in a scene to see if that changes anything? User TSDREX says in this thread that Point Lights were causing substantial slowdown on his 970-equipped computer.