So, I got restless and tried this again with 13.2.
I do not get the nag to re-scan anymore (which is good), but now I have the issue described in this thread:
http://forum.xbmc.org/showthread.php?tid=197373&page=2.
The "slowness" doesn't exist until I load all the music into the library: ~50k songs, ~3k albums, ~6500 artists.
I tried portable mode (as someone suggested) and this made no difference. Whether I copied the userdata folder or did a normal scan it can take upwards of 1 minute to get back from artist view or album view to the previous screen. XBMC shows it is working, then not responding and then works fine again.
The good news is that when I use MusicPump to select artists, albums and play them there is no lag in XBMC at all. So, it is definitely something related to the user interface within XBMC when switching screens. As I use MusicPump on a dedicated Android device specifically for playing music this situation is workable, though not ideal.
I also have problems with smooth video playback when the system has been on for a few days (with 12.3). Others have reported this does not go away with 13.2, so I will see.
Should I...
(1) Try and redo my system with OpenElec and eliminate the playback issues and GUI slowness, but lose all my artist images or...
(2) Stick with what I have got and find a way to shutdown and restart the system at night to (hopefully) eliminate the playback chopiness. Does someone have an add-on to do this?
Thanks!
Brian