We have nearly 6K queues in our current setup. As SwiftMQ becomes unresponsive after all the receivers have started for the queues. We have also made changes as suggested by http://www.swiftmq.com/developers/tuning/index.html.
What we have observed is whenever the receivers reach the 6K mark during startup the application stops responding. I am sure we are missing a small point because SwiftMQ should be easily able to handle this much queues simultaneously.