The tcp_nodelayack tunable

The tcp_nodelayack option prompts TCP to send an immediate acknowledgement, rather than the usual 200 ms delay. Sending an immediate acknowledgement might add a little more overhead, but in some cases, greatly improves performance.

Performance problems have been seen when TCP delays sending an acknowledgement for 200 ms, because the sender is waiting on an acknowledgment from the receiver and the receiver is waiting on more data from the sender. This might result in low streaming throughput. If you suspect this problem, you should enable the tcp_nodelayack option to see if it improves the streaming performance. If it does not, disable the tcp_nodelayack option.