You should consider load balancing if the message flow rate requirements between publishers and subscribers are greater than the throughput that a single Broker, or Brokers belonging to a single Broker Server, is able to manage.

A typical situation for implementing a load-balancing solution is for high-volume guaranteed messages. This category refers to messaging environments with high-volume flow of guaranteed messages between publishers and subscribers. Since a Broker Server's throughput is constrained by its local disk performance, a single Broker Server may be unable to handle the message flow throughput.