Why is my ActiveMQ consumer slow?

Issue

• While running my consumer, I've seen it stop processing messages for a period of time. It then starts again. It seems relatively consistent. It also appears to get worse the more consumers that I add to such an extent my consumers were too slow to meet my SLA's.

• We use a queuePrefetch="1" on our queues, and the app consumes the messages about 2.5 times slower than a JMS Broker from another vendor.

-We are experiencing significant slowdown in our production amq/fuse 6.2 environment - admittedly it is very busy at present but any pointers to help increase/tweak settings would be most appreciated.