I’ve been experimenting (again 
) with RoonServer on a Mac Mini with 8GB RAM + SSD for Mac OS and Roon. My music library is on a WD MyBook 3TB, from a mounted SMB share. My renderer is a Bryston BDP-1.
One thing I’ve observed is that RoonServer is sensitive to file access delays. In other words, I’ve noticed that if there is any delay in loading a file, you will hear delays in playback between tracks. This was noticeable in my system when playing longish tracks that have gapless transition to the next track (think: classical movements).
If the HDD holding your music spins down (read: sleeps), you may experience gaps in playback. This was especially noticeable in my system using the WD MyCloud as the SMB host for my Roon library.
Even though I have sleep disabled on the WD MyCloud, I ultimately solved this by downloading the Mac OS app: Disksomnia, form the Apple App Store, and configuring it to touch the mounted share every 30 seconds whenever Roon is running.
I’ve been running with Disksomnia all through the holiday weekend and I’ve not experienced another gap in playback, even though this was common beforehand - especially between tracks #1 and #2.
Previously, on the BDP-1, playback was via MPD and this an area where MPD excels… even loading the same tracks from the same WD MyCloud NAS share, I’ve never had these delay problems. I believe MPD is more aggressive in pre-fetching the next track.
Maybe consider adding a configurable “touch” for remote libraries - defaulting to every 30 seconds only while music is playing to ensure that file loads are quick for subsequent tracks.