I don’t know the specifics about how multicast works in Roon. It is a way for computers/devices to talk to each other.
From what I know, multicasting helps Roon communicate to various devices. The router in your system will help make that happen. You don’t need switches to be part of this. If you have a simple unmanaged switch it will just pass the multicasting communication to the affected devices.
If you have dropouts or problems finding devices on the network, it could be because the multicasting is being affected. A router might not be set right or the switch may interfere with multicast communication in some way. This does not really affect sound quality. But if you have dropouts or other communication issues you would call this bad performance.
To your original question, an unmanaged switch like the Netgear is good because it is unmanaged and freely passes the signal to devices without getting in the way.
Maybe someone with a better understanding of multicasting can explain this better, as I am certainly no expert here.