[Koha] Cleanup of zebraqueue mysql table

I don't see where entries are ever deleted (once marked "done") from the zebraqueue mysql table. Can anyone point me at this code. If its missing, it looks like it should be added to rebuild_zebra.pl. Also, can someone comment on the time taken by rebuild_zebra.pl vs the older zebraqueue_daemon? We have around 13K records. -Doug-