This paper discusses how to decrease and stabilize network latency in a Beowulf system. Having low latency is particularly important to reduce execution time of High Performance Computing applications. Optimization opportunities are identified and analyzed over the different system components that are integrated in compute nodes, including device drivers, operating system services and kernel parameters. This work contributes with a systematic approach to optimize communication latency, provided with a detailed checklist and procedure. Performance impacts are shown through the figures of benchmarks and mpiBLAST as a real-world application. We found that after applying different techniques the default Gigabit Ethernet latency can be reduced from about 50 <img border=0 width=32 height=32 id="_x0000_i1025" src="..\..\..\..\..\img\revistas\cleiej\v15n3\3a040x.png" alt="μ " class=math>s into nearly 20 <img border=0 width=32 height=32 id="_x0000_i1026" src="..\..\..\..\..\img\revistas\cleiej\v15n3\3a041x.png" alt="μ " class=math>s.