I'm designing an application which will have a network interface for feeding out large numbers of very small metadata requests. The application code itself is very fast, basically looking up data cached in memory and sending it to the client.

What's the absolute lowest latency I can get for a network application server running on a linux box? This will be an internal app running on gigE with no authentication. Any language/framework considered, with a preference for C, C++, or Python. Likewise for protocol, although HTTP would be nice.