While this doesn't answer the question, one thing I've found (see my other comment for why I don't care for 0mq) is that Rabbit really doesn't like to be full a

While this doesn't answer the question, one thing I've found (see my other comment for why I don't care for 0mq) is that Rabbit really doesn't like to be full as a queue. It really requires that you can eat messages off as quick as you can put them on the queue, or else it slows down -- which means you can't pull them off as quickly, and then things basically get to "cascade failure" type problems. Maybe others have other experiences - Rabbit is fast, but I'd probably evaluate other options if you want your queue to actually, well, queue.