Excellent ressource for php programmers
# If a method can be static, declare it static. Speed improvement is by a factor of 4.
# echo is faster than print.
# Use echo’s multiple parameters instead of string concatenation.
# Set the maxvalue for your for-loops before and not in the loop.
# Unset your variables to free memory, especially large arrays.
# Avoid magic like __get, __set, __autoload
# require_once() is expensive
# Use full paths in includes and requires, less time spent on resolving the OS paths.
# If you need to find out the time when the script started executing, $_SERVER[’REQUEST_TIME’] is preferred to time()
# See if you can use strncasecmp, strpbrk and stripos instead of regex