  Developing an application with high performance through the code optimization
places a greater responsibility on the programmers. While most of the existing
compilers attempt to automatically optimize the program code, manual techniques
remain the predominant method for performing optimization. Deciding where to
try to optimize code is difficult, especially for large complex applications.
For manual optimization, the programmers can use his experiences in writing the
code, and then he can use a software profiler in order to collect and analyze
the performance data from the code. In this work, we have gathered the most
experiences which can be applied to improve the style of writing programs in C
language as well as we present an implementation of the manual optimization of
the codes using the Intel VTune profiler. The paper includes two case studies
to illustrate our optimization on the Heap Sort and Factorial functions.
