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RabbitMQ 1.6 has an option to set a pre-fetch limit. So we simply set the pre-fetch limit to 1, and our EventMachine loop runs nice and fast now. You'll want to tweak your pre-fetch limit depending on how long it takes to process each message. If you can churn through a hundred messages a second, you probably won't even notice this problem and the prefetching will help you, but if it takes you a few seconds (or minutes) per message, you'll wonder why things aren't popped off the queue for several minutes (or hours).