I disagree. This is mainly a function of the capabilities of the NAS. The baby DS108 the OP has is very underpowered, so yes, this would be a true statement for them. But a larger NAS will generally have WAY higher performance than a locally attached drive. Any of the Synology “Plus” series units should be fine, especially if you expand the RAM in them.
With a suitably sized NAS, the only drawback with Roon is the automatic ingest of new music, since SMB directory watches are inconsistent compared to locally attached file systems. For me, personally, that’s a benefit, however. When I am adding music, it gives me a chance to insure it is properly curated before Roon goes to scan it. Starting a manual scan is a non-issue for me.
(I keep my library on a much larger NAS, FWIW. And I’ve never had issues with Roon’s overall performance or library scanning.)
I got tired of all the delays in updating my library from my Synology D218+ I attached a 4 TB Western Digital USB hard drive to the back of my Rock and the difference is just night and day. I use the Nas for Plex and back up and I use Chronosync to keep everything synchronized. This works really well.
This is all great discussion, thanks all. It’s comforting to see I’m not alone and that there is a solution. Just be good for @Roon to give some guidelines around this. I’m in the process of building a ROCK with internal drives but this is a month off so have to decide on a temporary solution. I guess this is the ideal but at that point you may as well build a PC with an internal NAS.