Queue style systems usually start running into limits of the disk subsystem. Kafka is distributed log style. What that means is 'sharding' is basically built

Queue style systems usually start running into limits of the disk subsystem. Kafka is distributed log style. What that means is 'sharding' is basically built into kafka while MQ you need to build it in one layer up. Kafka can run into the same issues if you pick a poor hash for your partition. The messages per second really depends on the size of the messages too. For example in one of my tests I was hitting well over 10k-20k messages per second if the message size was 10 bytes (if my memory is working today). It dropped off dramatically as size grew. The limit was directly determined by disk and cpu. Switching to a different stack would mitigate some of that. But in the end if you expect scale (millions of messages an hour) you need a distributed system in there somewhere eventually. Would I personally reach for kafka out of the box? Not so much. I personally think it is quite a monster to get setup correctly. If you need dual datacenter up time it also becomes very expensive as you need to buy cloudera or confluent. Or have a plan to manage it yourself which will be 'interesting'.