Poor Reliability Is Worse Than Poor Efficiency

Poor Reliability

Poor Efficiency

Poor reliability may not be readily apparent and it may be inconsistent. The difficulty in detecting poor reliability contributes to the difficulty in finding a fix for the problem. Efficiency, on the other hand, is usually consistent and easier to isolate. Making a redesign or refactor of the code for better efficiency easier than fixing poor reliability. Which "needle" do you think is harder to find?


Reference:
I. Sommerville. 1992. Software Engineering, Section 20.0. Addison-Wesley., Reading, MA, USA.