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.