Hopefully this may help someone else out also. I had an issue with the StreetDedck music module when I used the "Play all" feature it would take a considerable amount of time to load all of my music (120GB in my case) once loaded performance was a little sluggish.

The issue was with the .M3U files, my music is sorted by folders indicating each particular artist then subfolders indications albums by said artist. Each of my album folders contained a .M3U file used for playlist. When I indexed using Streetdeck this loaded over 1000 playlist. I performed a search for *.M3U files deleted them them all, after doing so StreetDeck will almost instantaniously load all my music with the "Play all" feature, the performance is nolonger sluggish.