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

It's obvious, but creating objects is also costly, so for ex. if you need a timestamp doing a time() is double faster than doing a date_create()->getTimestamp.

for ($a=1;$a<1000000;$a++) {
  $e = time(); // In my tests about 2x faster than:
  //$e = date_create()->getTimestamp();
}