What are some good PHP performance tips?

Question

I\'ve heard of some performance tips for PHP such as using strtr() over str_replace() over preg_replace() depending on the situation.

Answer 1

PREMATURE OPTIMIZATION IS THE ROOT OF ALL EVIL

And that's the most important tip you need. If some day you have a real performance problem, profile your application, detect the compromised areas, and came here to ask again :)