Simple source code changes can often result in substantial performance enhancements using modern optimizing compilers on high-end embedded processors. But, why is performance necessary? After all, the capabilities of modern microprocessors dwarf the capabilities of 1980-era supercomputers. First, the average case response time of a real-time system is irrelevant. It is the worst-case response time that guards against a dropped call, a misprint, or other error conditions in a product. In other words, performance is necessary to minimize the response time of one’s system, thereby achieving product reliability.
Second, increased performance allows for the implementation of more features without compromising the integrity of the system. Conversely, performance might be used to select a cheaper microprocessor or one that consumes less power.
Original Article can be read at Guidelines for writing efficient C/C++ code Greg Davis , Green Hills Software, Inc. (04/05/2006 9:00 AM EDT)