I'm always surprised when I look at the top questions and it's full of stuff like "why does $#^$&%*# work in perl" or "what does c=c++-1 equal."

Not only that, its also completely irrelevant for 99% of developers. My bet is that most of the (currently) 167 up votes did not have this specific problem.

The Shift vs Division question was also already asked many times on Stackoverflow in the past.

It's a bad question, though. Either you know the answer, or the peephole optimizer will do a better job than you will, and therefore you should use what's most readable. I agree with GP that these kinds of questions are unfortunate noise at stackoverflow.