There's a beanstalkd queue, which gets filled with a lot of tasks say every 10 minutes and it is top priority that each task is processed ASAP. Task can take more that a few milliseconds to complete for there are calls to third-party services, which tend to timeout every now and then.
So since PHP doesn't have multithreading, one option would be to create a lot of idle workers, which would try to reserve a task, but it is likely to take too much RAM, which may not be available on those boxes.
Is it a good idea to use PHP-FPM to adjust the number of workers and save some RAM? Is it production-ready? Are there better solutions?