Next are some tips for writing highly efficient PHP codes. They are described below:
0. Use single quote to replace double quote, this will be better since PHP will serach for variables in double quoted strings. Note, only echo can do this;
1. If we can define methods of a class as static, then do it. It will increase access speed by 4 times;
2. $row["id"] is 7 times faster than $row[id];
3. echo is faster than print, and also use echo's multiple parameter format such as echo $str1,$str2 instead of echo $str1.$str2;
4. When using for loop, make sure the maximum number of executions instead of calculating maximum execution times in each loop. Use foreach if you can;
5. unset unused variables especially for those large data structures like array to release memory;
6. try best to avoid using __get,__set and __autoload;
7. require_once() cost much;
8. use absolute path when using include() function, it will short the time for searching the included file;
9. If you want to know the execution time of a script, using $_SERVER["REQUEST_TIME"] is better than using time();
10. using functions to replace regular expression to realize the same functions;
11. str_replace() is faster than preg_replace() and strtr is 4 times faster than str_replace();
12. using switch is better than using if else;
13. using @ to hide error message is less efficient;
14. after finish using database connection, close it;
15. using built-in functions whenever you can