I had to go back to svn-1236 to get good initial scan performance. 20301 songs in 161 seconds (while the system is basically idle beyond Firefly and, at this point, with a very healthy system cache.) I also re-installed svn-1206, and it finished in 160 seconds, too.
Okay, I can track this down, then.
Other related business: Can you add a “Rescanning database complete” message (or some statistic) to the Firefly log once it finishes a rescan. All I ever see in the log is “Rescanning database” at minimal debug levels, without a clue when it actually finishes. (I have no idea how long rescans take…)
I’ll do something with that.