From quota:
I once emailed a question to a C compiler developer: “Which is faster, ++i or i++?”
His reply was: “By emailing me this question, you have already wasted more CPU cycles than you will ever save in your whole programming career by choosing one incrementation form over the other. Use the form that is most clear and convenient in the context of your code.”
In other words, a given code “optimization” might be so insignificant that it’s not worth the time to consider it.