Hi,
As far as compression improving speed...I was thinking more for internet connections with little bandwidth. You are right that most of the time latency is the problem. However, the ENET plugin right now sends everything as a text string...this has potential to send very large packets which "could" consume precious bandwidth. So it would be nice to make it more efficient. Odds are though it doesn't help many real world game situations..as you mention because the problem is latency.