What is your latency now and why do you need to improve it?
I wanted to improve my latency for voice and gaming. I live in Asia, but tend to play with people in California, so I want to do as much as I can to lower my latency (given the distance). I ran some trace routes and the latency on my end is >1m (as suggested by other posters) so I guess I'm doing as much as possible?
1m is 1minute?
Ping your firewall/router. One to two miliseconds is quite normal for a home router/firewall over a wired connection. Now for some math. The great circle distance from Hong Kong to San Fransisco (Asia to California) is 11147 km. If you were to run a single optical fiber between those two citys in the most direct path possible, there would be a 55ms delay for a signal traveling one way. So for a round trip ping, physics says your time will be 110ms at a theoretical minimum.
For me, in Texas, a ping to a Hong Kong IP address is about 218ms. 160ms of that is physics. That leaves 58ms. 12ms is the hop from my router to my ISP gateway. Down to 46ms. That is mainly composed on hops across the US. My internal network contribution? 1.04ms. Everything else is out of my control.
All that said, depending on what you are doing, disabling Nagle's algorithm (TCP_NO_DELAY) might actually help depending on the the application, especially since the long path delay can have a similar effect as TCP delayed acknowledgedment (again, depending on the application). One other thing to consider. None of this matters if the application uses UDP for communications. Also, TCP_NO_DELAY is usually set at the connection level by the application if it will benefit from it.