1. If a method can be static, declare it static. Speed improvement is by a factor of 4. 如果一个方法可静态化，就对它做静态声明。速率可提升至4倍。
2. echo is faster than print. echo 比 print 快。
3. Use echo’s multiple parameters instead of string concatenation. 使用echo的多重参数(译注：指用逗号而不是句点)代替字符串连接。
4. Set the maxvalue for your for-loops before and not in the loop. 在执行for循环之前确定最大循环数，不要每循环一次都计算最大值。
5. Unset your variables to free memory, especially large arrays. 注销那些不用的变量尤其是大数组，以便释放内存。
6. Avoid magic like __get, __set, __autoload 尽量避免使用__get，__set，__autoload。
7. require_once() is expensive require_once()代价昂贵。
8. Use full paths in includes and requires, less time spent on resolving the OS paths. 在包含文件时使用完整路径，解析操作系统路径所需的时间会更少。
9. If you need to find out the time when the script started executing, $_SERVER[’REQUEST_TIME’] is preferred to time() 如果你想知道脚本开始执行(译注：即服务器端收到客户端请求)的时刻，使用$_SERVER[‘REQUEST_TIME’]要好于time()。
10. See if you can use strncasecmp, strpbrk and stripos instead of regex. 检查是否能用strncasecmp，strpbrk，stripos函数代替正则表达式完成相同功能。
11. str_replace is faster than preg_replace, but strtr is faster than str_replace by a factor of 4. str_replace函数比preg_replace函数快，但strtr函数的效率是str_replace函数的四倍。
12. If the function, such as string replacement function, accepts both arrays and single characters as arguments, and if your argument list is not too long, consider writing a few redundant replacement statements, passing one character at a time, instead of one line of code that accepts arrays as search and replace arguments. 如果一个字符串替换函数，可接受数组或字符作为参数，并且参数长度不太长，那么可以考虑额外写一段替换代码，使得每次传递参数是一个字符，而不是只写一行代码接受数组作为查询和替换的参数。
13. It’s better to use select statements than multi if, else if, statements. 使用选择分支语句(译注：即switch case)好于使用多个if，else if语句。
14. Error suppression with @ is very slow. 用@屏蔽错误消息的做法非常低效。
15. Turn on apache’s mod_deflate 打开apache的mod_deflate模块。
16. Close your database connections when you’re done with them. 数据库连接当使用完毕时应关掉。
17. $row[’id’] is 7 times faster than $row[id]. $row[‘id’]的效率是$row[id]的7倍。
18. Error messages are expensive. 错误消息代价昂贵。
19. Do not use functions inside of for loop, such as for ($x=0; $x
