There is a server for measurements running on Ubuntu in my lab. And there is C program, which receives data through TCP connection and should as soon as possible send a reply. 

**Configuration**

* CPUs: 2 processors x 4 cores - Intel(R) Xeon(R) CPU E5345 @ 2.33GHz
* RAM: 12 GB
* NIC: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller / 82546EB Gigabit Ethernet Controller
* Network switch: Cisco Catalyst 2960
* Data info: Data blocks come approx. each 10 milliseconds. Data block size is approx. 1000 byte.

Network latency when receiving packets is very critical (tens of microseconds are important). I optimized the program to the maximum, but I have no experience tweaking Ubuntu.

What can be configured in Ubuntu to reduce the local delay of processing/sending packets?