On my laptop, using a musicmetadata set of 29000 records.

before:
2006-02-11 19:39:59.270 AllMusic: Avg: Tree build of 'directory' took 38519 Mcycles, wall time 24.15s
2006-02-11 19:40:32.018 AllMusic: Avg: Tree build of 'artist album title' took 10444 Mcycles, wall time 6.55s
2006-02-11 19:41:07.797 AllMusic: Avg: Tree build of 'splitartist artist album title' took 11411 Mcycles, wall time 7.16s
2006-02-11 19:41:48.855 AllMusic: Avg: Tree build of 'splitartist1 artist album title' took 13095 Mcycles, wall time 8.21s

after:
2006-02-14 21:46:21.290 AllMusic: Avg: Tree build of 'directory' took 9586 Mcycles, wall time 6.01s
2006-02-14 21:46:54.353 AllMusic: Avg: Tree build of 'artist album title' took 10544 Mcycles, wall time 6.61s
2006-02-14 21:47:28.358 AllMusic: Avg: Tree build of 'splitartist artist album title' took 10845 Mcycles, wall time 6.80s
2006-02-14 21:48:01.783 AllMusic: Avg: Tree build of 'splitartist1 artist album title' took 10660 Mcycles, wall time 6.68s

Reading metadata from DB consumes ~5 secs of all of the above readings.