As good as the processor is claimed to be, I will say that Affinity photo definitely slows under heavy usage with high DPI. Now, this may be a program fault, and not hardware. I have high hopes for photoshop efficiently, but in truth, I prefer affinity photo at this point.
I don’t think Affinity has been updated for a couple of months. Perhaps they need to optimize it for the 2018 pros or latest iOS?
But I do think it will be interesting to see what happens when full photoshop comes out and people start comparing performances with it.