I had this problem, moreso with Periscope player than SubAir,
and the only surefire answer was to move the music files & playlists onto the PC where Subsonic was running.
Also building playlists in the 8hr range helped.
Almost no matter what I did, the slow communication between my Promise NS4300N
and whatever machine had Subsonic just bogged it down.
Having just recently (yesterday) migrated to a QNAP TS419P II with Subsonic installed,
I'm hoping to have better performance. Single-song playback is fine (though I've heard of transcoding issues).
The challenge I've got now is formatting the playlists in MediaMnkey on the PC
so Subsonic on the NAS can load them...
-G
12,617 artists
4,284 albums
54,593 songs
460.15 GB (~ 7,148 hours)
