We are currently doing performance tesing on a SOA/BPEL/JavaCAPS system that sends SOAP messages to a JBossMQ queue. The BPEL and IEP performance is very good, but when it comes to putting messages onto the queue, the JBoss performance is quite spiky on the graph, oscillating between good and bad. The queue is an old version I think (1.4?) but that is not under our control.
What could cause this - could there be a 'housekeeping' process that kicks in regularly?

Apologies if the JBoss Messaging forum is not the most appropriate one, but I would appreciate any help.