I recently stumbled on an interesting TCP performance issue while running some performance tests that compared network performance versus loopback performance. In my case the network performance exceeded the loopback performance (1Gig network, same subnet). In the case I am dealing latencies are crucial, so TCP_NODELAY is enabled. The best theory that we have come up with is that TCP congestion control is holding up packets. We did some packet analysis and we can definitely see that packets are being held, but the reason is not obvious. Now the questions...I recently stumbled on an interesting TCP perfo