Since you seem to be using FireFly as a media server anyway and with that many tracks and performance trouble, I propose you might want to give MediaMonkey a try instead of iTunes:
Oh, almost forgot to stay on topic: 12582 legal tracks.
I tried MediaMonkey. It burnt to a crisp. iTunes bogs down at about 20-30K tracks, and MediaMonkey did better at about 60K, but nothing seems to work. I’ve used http://www.ampache.org with great success but the interface is sorely lacking. I’ve also tried Jinzora but it implodes with only about 5-10K tracks and after that is completely unusable.
I’ve tried Google Desktop Search with the MP3 plugin (not very useful). Really there is nothing out there that can handle the number of tracks efficiently. I have to wait for 60GB iPod’s to be the standard and 50K+ tracks become the norm before I’ll see any improvement I guess. The new iTunes 7 made no difference, but at least I am not seeing the bugs others have reported.
Maybe I don’t follow your comment about mediamonkey? Is there a way to use mediamonkey with the Firefly server?