I have found the post by Reinhold Webber, which provide good techniques and methods for PHP performance and optimization. I have tried to add more explanation to the points posted by Reinhold Webber.
- If a method can be static, declare it static. Speed improvement is by a factor of 4.
- echo is faster than print and print_r.
- 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.