You should already know the answer... (Score 1)

Maintainability is much more important than optimization. If you do find a slow section of code, it can almost always be optimized in a way that leaves it maintainable. Real hand-optimization involves using a better algorithm, reducing the number of function calls, reducing branchs, and at worst, adding more variables to avoid performing the same calculations repeatedly within a loop. None of these require you to compete in an obfuscated C contest!