Roon uses .NET under the hood. Microsoft’s implementation is better, more stable, and more intensively engineered than Mono, which we use on Macs. As a result, Windows scales better for large collections, and has a performance edge on the same hardware.
Windows machines are also better at accessing SMB shares than mac machines. They perform better when working with SMB shares, and they pick up real-time changes more reliably.
In terms of audio, Mac has a slight edge in terms of stability. This is mostly because many more DACs use (stable, well behaved) stock USB Audio 2.0 drivers on Mac, whereas on windows, there is a lot of variability in driver behavior from manufacturer to manufacturer. Almost all of our audio stability problems result in us implementing workarounds for less-than-ideal driver behavior, especially when it comes to ASIO drivers. There are also many fewer hardware/OS permutations to test, so when we perform QA, we get better coverage.
Over here, some of us run on Windows and some on Mac. I wouldn’t let any of this sway your OS decision too hard.