On brokers with many queues, we find that upon disconnects of many components simultaneously, the broker immediately begins to slow. My suspicion is due to the queue auto-deletion behavior, where we do an ArrayList#remove(Object) in HierarchalObjectRepository#unRegisterListener which I believe is linear at least in the number of queues. With over a million queues, this becomes incredibly slow. Perhaps we can optimize the find of these listeners (maybe a map with an ID)?