I got my wife's 2200 image library "titled" in about 5 minutes. I started with a few images, and keep increasing the number of images processed - and it did several hundred at a time without any problems - and pretty quickly too.
I ran into two issues:
(1) The first couple of times you try to run the service script, it fails with an error. Restarting the computer seemed to fix that.
(2) I have an administrator account and my wife has a normal user account on her iMac (I am trying to keep her safe). I originally created the Photo Service in my account - and it didn't show up in her account. I recreated it in her account, and it runs fine. I haven't seen anything that says how to create an service for all user account - which would be a handy option.
Thanks again for this very helpful fix.
David