Purge users not attached to tickets

I need a fast, reliable way to purge accounts from RT that are not associated with a ticket. Our deployment allows anyone to email the system & denies any users the ability to log into the site or register. Only “Staff” is allowed to log in. I have too many users copy/pasting improperly or fat fingering email addresses when manually typing them in. The department also is refusing to actively maintain their user information so it’s falling on IT. If I remember, there is a bug in 4.4.2 that prevents user Shredding from working correctly. I do have a plug in for Managing Auto Created Users, but I can’t delete any more than 3 at a time and even that takes 10+ minutes or more. I can’t tell if its stemming from the aforementioned Shredder bug or the plugin itself.

Does anyone have any suggestions>