In the interest of some outside figures, how have you found this to scale? I implemented a similar solution as more of a stopgap until I had the time to get RabbitMQ installed with a "proper" worker dispatcher (more moving parts but less stress on the DB). I mostly ask because we implemented it for our notification system where we had to generate a send large batches of custom emails which was bogging down the page (and hard to debug where in the chain we were getting failed messages).