I am playing fine now, but I had to switch aspect ratio to 16:9 (from 16:10) and downgrade to 2880 x 1620 and medium quality across the board for everything but texture quality. This is on a 27" iMac with a dedicated Graphics card and an i7 proc.
The Mac version has taken a performance hit, there is no question. I used to be able to run it at 30 FPS at high quality and 5120 x 2880.
I know macOS is not a priority but hopefully Mac team takes a beat to improve performance for us.
