hi,
for systemd, https://github.com/rclone/rclone/wiki/Systemd-rclone-mount
about the mount command, be sure you need all those flags.
--fast-list does nothng on a mount.
try
/etc/rclone/rclone mount maxsuitecrypto:V/Music /mnt/MPD/LocalStorage/Music --daemon --allow-other --read-only --no-checksum --no-modtime --vfs-cache-mode full --dir-cache-time 72h --log-level ERROR
about scanning, it depends on what runeaudio does when it scans each file.
if it is just filename, filesize, etc, then the scan should go quick.
if it reads some of the data of each file, that would be much slower.
i know nothig about runeaudio and how it performs.
and i find my pi units are slow in strange ways.
to speed to the scan, you can try to prime the cache.
this is a good post to read Slow scans after library expanded
my friend, @VBB has a very simple set of scripts.
one script for read only mount.
one script to prime the mount.