if it is interesting to anyone, it seems that it takes about 35% longer to pull the mb artist id from mutagen and then get the name from the api than just the latter (i.e., if i engage the mpd protocol instead of using mpc and return the mb artist ids that way)
```
$ time { i="$(mutagen "/library/music/Warren Haynes/Various Artists -- Warren Haynes Presents: The Benefit Concert, Vol. 01 (2007) (mp3)/01-10 - The Derek Trucks Band with Susan Tedeschi -- Just Won't Burn.mp3"|grep -i musicbrainz\ artist\ id)"; i="${i##*=}"; i="${i%%\/*}"; ./retrievename "$i" ; } ; time ./retrievename bb110dbc-8daa-407f-a04b-f569e7a5ee7e
Artist Name: The Derek Trucks Band

real	0m0.526s
user	0m0.167s
sys	0m0.028s
Artist Name: The Derek Trucks Band

real	0m0.371s
user	0m0.054s
sys	0m0.013s

```