I fully agree with that. Those kinds of optimization may be sensible to tighten some critical inner loops of your code. But especially there you should avoid h

I fully agree with that. Those kinds of optimization may be sensible to tighten some critical inner loops of your code. But especially there you should avoid high-level features anyway. Also, before trying to squeeze out performance that way, you might as well rewrite that part of your code in C, and let the C compiler perform real optimizations. However, chances are good that you don't even need that, as some intelligent combination of already existing fast PHP functions (implemented in C) usually does the trick.