So I've taken a default Xenforo install and imported two phpBB 3.0 boards into it. Database size is now about 750 MB. Merging the two boards has resulted in about 450 usergroups that we want to clean out. However, when we use the ACP to delete a group, the request hangs and I eventually get: I've got the timeout set to 50 seconds. It should not be taking this long on a database of this size. I've checked the InnoDB status and it appears that the transaction running this query hangs waiting for a lock to be released from somewhere. Looks like a deadlock. I'm not really sure where to go. This might be a bug that needs reporting. To add some info, I have another Xenforo install running with InnoDB on the same server (though it is smaller) and do not have this issue - I can create a delete usergroups just fine. Also, I've tried copying this site over to a completely different server and I still encounter the same issue. Any ideas?