Ah, that's a shame. What Mac did you try this on? Just curious really as 1fps is something I can't even replicate on my Intel Mac.
On my 2018 Intel MBP, first running at 2560x1600 was around 25-30 fps ish. 1680x1050 hit 60fps. While the highest resolution of 3360x2100 was around maybe 20fps.
However, on my Mac (base M1 mini) 1440p was hitting 60fps without a hitch. Gradually tap up the resolution and I can see the performance tail off and at 4k, I'm seeing maybe 20-30 fps.
I was about to pop here to thank the dev for the Mac compilation and Apple Silicon support.