We mentioned this in the release notes for 1.7. Streaming vs files make no difference on performance at all. They impact the system identically.
There was a time where Roon OS performed the same as Roon on Linux/Mac, and you needed to use Windows if you had more than approximately 300,000 tracks. But that changed with 1.7 – Mac/Linux/Windows are the same as before, but Roon OS (ROCK and Nucleus) is even better performing than Windows now.