For the benefit of anyone wondering…
On the basis of recent rides and using a bit of quick and dirty maths extrapolating from my own GPU, I reckon to ensure 60fps in 4K at all times on Makuri Islands you’d need an RTX 2080 Super or 3060 Ti as a minimum; 2080 Ti or 3070 to be safe. This is leagues above the requirements elsewhere in the game, where generally a GTX 970/1060/1650 Super is fine.
Note that this is ignoring the obvious and separate CPU bottleneck problems which also plague Makuri, I’m talking purely the GPU performance requirements to brute force it when not otherwise limited.
Personally think this is absolutely ridiculous.