An HL7 interface can be thought of as an assembly line. When your interface needs to handle a high volume of messages, it's often not that important if it takes five minutes for one message to go through the entire system.

What matters is the overall throughput. If you need to process 1000 messages per second, it's very important that the processing of one message doesn't hold up the processing of the next one. As much as possible, your design should allow each message to be processed independently of other messages to avoid one message holding up another.