Apologies for not making this clear, I was definitely assuming a LIFO buffer would drop the oldest message when full, since dropping the newest message has the

Apologies for not making this clear, I was definitely assuming a LIFO buffer would drop the oldest message when full, since dropping the newest message has the issue you describe. In that case, for a prolonged period of ingress slightly over egress, the buffer will contain the N most recently received messages that haven't been transmitted, which seems optimal, but _also_ will have no queueing-induced latency for new messages. If there's a gap in the incoming data stream, a LIFO buffer would emit the most-recent (and most likely to be useful) data first. Most importantly, there's now no performance drawback for making the buffer bigger, so tuning it is way less dependent on your expected operating environment. One other optimization that would probably make sense in a practical implementation is a "max age" limit on things popped from the stack, so that an old message can't sit around for several seconds if the ingress rate happens to exactly matches egress. This limit can be fairly long though (~1s is fine), since it's just trying to approximate when a higher-level protocol would already have completed a full roundtrip and requested retransmit.