I've finally figured out what was causing this. Viewing the contents of a queue by clicking the queue name in the browser interface will spawn a consumer to view all of that data. The more messages in the queue the longer the cpu spike will last. These consumers don't actually consume the messages; it appears to be more of an indexing or listing of the queue contents. Once they have all been listed the consumer goes away and the cpu load drops back to normal.
-- Sent from: http://activemq.2283324.n4.nabble.com/ActiveMQ-User-f2341805.html
