PHP performance

Question

What can I do to increase the performance/speed of my PHP scripts without installing software on my servers?

Answer 1

including files is slow, and requiring them is even slower. If you use __autoload for including every class then that will add up. for example.

I'm always a bit wary of trying to be too clever in terms of code optimisation, if it sacrifices code clairty. If you need to make code obscure to make it fast, would it not be cheaper to upgrade hardwear instead of wasting your time trying to tweak code? Processor cycles are cheaper than programmer cycles, after all.