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; $x < count($array); $x) The count() function gets called each time. 尽量不要在for循环中使用函数，比如for ($x=0; $x < count($array); $x)每循环一次都会调用count()函数。

20. Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function. 在方法中递增局部变量，速度是最快的。几乎与在函数中调用局部变量的速度相当。

21. Incrementing a global variable is 2 times slow than a local var. 递增一个全局变量要比递增一个局部变量慢2倍。

22. Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable. 递增一个对象属性（如：$this->prop++）要比递增一个局部变量慢3倍。

23. Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one. 递增一个未预定义的局部变量要比递增一个预定义的局部变量慢9至10倍。

24. Just declaring a global variable without using it in a function also slows things down (by about the same amount as incrementing a local var). PHP probably does a check to see if the global exists. 仅定义一个局部变量而没在函数中调用它，同样会减慢速度（其程度相当于递增一个局部变量）。PHP大概会检查看是否存在全局变量。

25. Method invocation appears to be independent of the number of methods defined in the class because I added 10 more methods to the test class (before and after the test method) with no change in performance. 方法调用看来与类中定义的方法的数量无关，因为我（在测试方法之前和之后都）添加了10个方法，但性能上没有变化。

26. Methods in derived classes run faster than ones defined in the base class. 派生类中的方法运行起来要快于在基类中定义的同样的方法。

27. A function call with one parameter and an empty function body takes about the same time as doing 7-8 $localvar++ operations. A similar method call is of course about 15 $localvar++ operations. 调用带有一个参数的空函数，其花费的时间相当于执行7至8次的局部变量递增操作。类似的方法调用所花费的时间接近于15次的局部变量递增操作。

28. Surrounding your string by ‘ instead of " will make things interpret a little faster since php looks for variables inside "…" but not inside ‘…’. Of course you can only do this when you don’t need to have variables in the string. 用单引号代替双引号来包含字符串，这样做会更快一些。因为PHP会在双引号包围的字符串中搜寻变量，单引号则不会。当然，只有当你不需要在字符串中包含变量时才可以这么做。