You can also achieve nearly the same level of performance by adding exclusions to Windows defender. I typically exclude the game process as I still would want folders scanned when updates / downloads are running. There's a noticable improvement to load times, streaming texture latency, and CPU utilisation.
I don't believe ReFS is contributing so much to the performance improvements seen when using Dev Drives. Removing storage filters from volumes can go a long way.
According to some benchmarking removing the storage filters offers a mild boost when compared to adding an exclusion and you don't have the benefit of some AV protection when other processes are accessing the volume like steam etc.
