PHP is a very fast programming language, but there is more to optimizing PHP than just speed of code execution. Here is the list of 30 short tips you can use for writing an optimized and more efficient PHP code. I considered myself a bit of a PHP pro until I started researching some of this stuff and realized that there is a whole realm of information out there about optimizing php that I didn’t know about. I hope you will be as surprised as I was about some of the things you might learn from this article.

  1. If a method can be static, declare it static. Speed improvement is by a factor of 4.
  2. echo is faster than print.
  3. Unset your large variables to free memory.
  4. require_once() is expensive
  5. Use full paths in includes and requires, less time spent on resolving the OS paths.
  6. If you need to find out the time when the script started executing, $_SERVER[’REQUEST_TIME’] is preferred to time()
  7. See if you can use strncasecmp, strpbrk and stripos instead of regex
  8. str_replace is faster than preg_replace, but strtr is faster than str_replace by a factor of 4
  9. 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.
  10. It’s better to use switch statements than multi if, else if, statements.
  11. Error suppression with @ is very slow.
  12. Turn on apache’s mod_deflate
  13. $row[’id’] is 7 times faster than $row[id]
  14. Do not use functions inside of for loop, such as for ($x=0; $x < count($array); $x) The count() function gets called each time.
  15. Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function.
  16. Incrementing a global variable is 2 times slow than a local var.
  17. Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable.
  18. Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one.
  19. 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.
  20. 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.
  21. Methods in derived classes run faster than ones defined in the base class.
  22. 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.
  23. 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.
  24. A PHP script will be served at least 2-10 times slower than a static HTML page by Apache. Try to use more static HTML pages and fewer scripts.
  25. Your PHP scripts are recompiled every time unless the scripts are cached. Install a PHP caching product to typically increase performance by 25-100% by removing compile times. Cache as much as possible. Use memcached – memcached is a high-performance memory object caching system intended to speed up dynamic web applications by alleviating database load. OP code caches are useful so that your script does not have to be compiled on every request.
  26. When incrementing or decrementing the value of the variable $i++ happens to be a tad slower then ++$i. This is something PHP specific and does not apply to other languages, so don’t go modifying your C or Java code thinking it’ll suddenly become faster, it won’t. ++$i happens to be faster in PHP because instead of 4 opcodes used for $i++ you only need 3. Post incrementation actually causes in the creation of a temporary var that is then incremented. While pre-incrementation increases the original value directly. This is one of the optimization that opcode optimized like Zend’s PHP optimizer. It is a still a good idea to keep in mind since not all opcode optimizers perform this optimization and there are plenty of ISPs and servers running without an opcode optimizer.
  27. Not everything has to be OOP, often it is too much overhead, each method and object call consumes a lot of memory.
  28. Do not implement every data structure as a class, arrays are useful, too
  29. Don’t split methods too much, think, which code you will really re-use
  30. Make use of the countless predefined functions