PHP optimisation tips

posted on 14 Aug 2010 14:14 by sisakday in computer

50+ PHP optimisation tips revisited

After reading an article some time ago entitled “40 Tips for optimizing your php Code” (and some others that are suspiciously similar), I decided to redo it, but properly this time with more accurate tips, providing references and citations for each and every one.

The result is this list of over 50 PHP optimisation tips…

Update: The list is more like 50+ PHP tips and tricks these days.

Enjoy!

 

  1. echo is faster than print. [Citation]
  2. Wrap your string in single quotes (‘) instead of double quotes (“) is faster because PHP searches for variables inside “…” and not in ‘…’, use this when you’re not using variables you need evaluating in your string. [Citation]
  3. Use sprintf instead of variables contained in double quotes, it’s about 10x faster. [Citation]
  4. Use echo’s multiple parameters (or stacked) instead of string concatenation. [Citation]
  5. Use pre-calculations, set the maximum value for your for-loops before and not in the loop. ie: for ($x=0; $x < count($array); $x), this calls the count() function each time, use $max=count($array) instead before the for-loop starts. [Citation]
  6. Unset or null your variables to free memory, especially large arrays. [Citation]
  7. Avoid magic like __get, __set, __autoload. [Citation]
  8. Use require() instead of require_once() where possible. [Citation]
  9. Use full paths in includes and requires, less time spent on resolving the OS paths. [Citation]
  10. require() and include() are identical in every way except require halts if the file is missing. Performance wise there is very little difference. [Citation]
  11. Since PHP5, the time of when the script started executing can be found in $_SERVER[’REQUEST_TIME’], use this instead of time() or microtime(). [Citation]
  12. PCRE regex is quicker than EREG, but always see if you can use quicker native functions such as strncasecmp, strpbrk and stripos instead. [Citation]
  13. When parsing with XML in PHP try xml2array, which makes use of the PHP XML functions, for HTML you can try PHP’s DOM document or DOM XML in PHP4. [Citation]
  14. str_replace is faster than preg_replace, str_replace is best overall, however strtr is sometimes quicker with larger strings. Using array() inside str_replace is usually quicker than multiple str_replace. [Citation]
  15. “else if” statements are faster than select statements aka case/switch. [Citation]
  16. Error suppression with @ is very slow. [Citation]
  17. To reduce bandwidth usage turn on mod_deflate in Apache v2 [Citation] or for Apache v1 try mod_gzip. [Citation]
  18. Close your database connections when you’re done with them. [Citation]
  19. $row[’id’] is 7 times faster than $row[id], because if you don’t supply quotes it has to guess which index you meant, assuming you didn’t mean a constant. [Citation]
  20. Use tags when declaring PHP as all other styles are depreciated, including short tags. [Citation]
  21. Use strict code, avoid suppressing errors, notices and warnings thus resulting in cleaner code and less overheads. Consider having error_reporting(E_ALL) always on. [Citation]
  22. PHP scripts are be served at 2-10 times slower by Apache httpd than a static page. Try to use static pages instead of server side scripts. [Citation]
  23. PHP scripts (unless cached) are compiled on the fly every time you call them. Install a PHP caching product (such as memcached or eAccelerator or Turck MMCache) to typically increase performance by 25-100% by removing compile times. You can even setup eAccelerator on cPanel using EasyApache3. [Citation]
  24. An alternative caching technique when you have pages that don’t change too frequently is to cache the HTML output of your PHP pages. Try Smarty or Cache Lite. [Citation]
  25. Use isset where possible in replace of strlen. (ie: if (strlen($foo) < 5) { echo “Foo is too short”; } vs. if (!isset($foo{5})) { echo “Foo is too short”; } ). [Citation]
  26. ++$i is faster than $ i++, so use pre-increment where possible. [Citation]
  27. Make use of the countless predefined functions of PHP, don’t attempt to build your own as the native ones will be far quicker; if you have very time and resource consuming functions, consider writing them as C extensions or modules. [Citation]
  28. Profile your code. A profiler shows you, which parts of your code consumes how many time. The Xdebug debugger already contains a profiler. Profiling shows you the bottlenecks in overview. [Citation]
  29. Document your code. [Citation]
  30. Learn the difference between good and bad code. [Citation]
  31. Stick to coding standards, it will make it easier for you to understand other people’s code and other people will be able to understand yours. [Citation]
  32. Separate code, content and presentation: keep your PHP code separate from your HTML. [Citation]
  33. Don’t bother using complex template systems such as Smarty, use the one that’s included in PHP already, see ob_get_contents and extract, and simply pull the data from your database. [Citation]
  34. Never trust variables coming from user land (such as from $_POST) use mysql_real_escape_string when using mysql, and htmlspecialchars when outputting as HTML. [Citation]
  35. For security reasons never have anything that could expose information about paths, extensions and configuration, such as display_errors or phpinfo() in your webroot. [Citation]
  36. Turn off register_globals (it’s disabled by default for a reason!). No script at production level should need this enabled as it is a security risk. Fix any scripts that require it on, and fix any scripts that require it off using unregister_globals(). Do this now, as it’s set to be removed in PHP6. [Citation]
  37. Avoid using plain text when storing and evaluating passwords to avoid exposure, instead use a hash, such as an md5 hash. [Citation]
  38. Use ip2long() and long2ip() to store IP addresses as integers instead of strings. [Citation]
  39. You can avoid reinventing the wheel by using the PEAR project, giving you existing code of a high standard. [Citation]
  40. When using header(‘Location: ‘.$url); remember to follow it with a die(); as the script continues to run even though the location has changed or avoid using it all together where possible. [Citation]
  41. In OOP, if a method can be a static method, declare it static. Speed improvement is by a factor of 4. [Citation].
  42. Incrementing a local variable in an OOP method is the fastest. Nearly the same as calling a local variable in a function and incrementing a global variable is 2 times slow than a local variable. [Citation]
  43. Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable. [Citation]
  44. Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one. [Citation]
  45. Just declaring a global variable without using it in a function slows things down (by about the same amount as incrementing a local var). PHP probably does a check to see if the global exists. [Citation]
  46. 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. [Citation]
  47. Methods in derived classes run faster than ones defined in the base class. [Citation]
  48. 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. [Citation]
  49. Not everything has to be OOP, often it is just overhead, each method and object call consumes a lot of memory. [Citation]
  50. Never trust user data, escape your strings that you use in SQL queries using mysql_real_escape_string, instead of mysql_escape_string or addslashes. Also note that if magic_quotes_gpc is enabled you should use stripslashes first. [Citation]
  51. Avoid the PHP mail() function header injection issue. [Citation]
  52. Unset your database variables (the password at a minimum), you shouldn’t need it after you make the database connection.
  53. RTFM! PHP offers a fantastic manual, possibly one of the best out there, which makes it a very hands on language, providing working examples and talking in plain English. Please USE IT! [Citation]

If you still need help, try #PHP on the EFnet IRC Network. (Read the !rules first).

 

 

http://www.hm2k.com/posts/50-php-optimisation-tips-revisited 

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PHP Optimization Tricks
There are a number of tricks that you can use to squeeze the last bit of performance from your scripts. These tricks won't make your applications much faster, but can give you that little edge in performance you may be looking for. More importantly it may give you insight into how PHP internals works allowing you to write code that can be executed in more optimal fashion by the Zend Engine. Please keep in mind that these are not the 1st optimization you should perform. There are some far easier and more performance advantageous tricks, however once those are exhausted and you don't feel like turning to C, these maybe tricks you would want to consider. So, without further ado...
1) When working with strings and you need to check that the string is either of a certain length you'd understandably would want to use the strlen() function. This function is pretty quick since it's operation does not perform any calculation but merely return the already known length of a string available in the zval structure (internal C struct used to store variables in PHP). However because strlen() is a function it is still somewhat slow because the function call requires several operations such as lowercase & hashtable lookup followed by the execution of said function. In some instance you can improve the speed of your code by using a isset() trick.

Ex.
if (strlen($foo) < 5) { echo "Foo is too short"; }
vs.
if (!isset($foo{5})) { echo "Foo is too short"; }

Calling isset() happens to be faster then strlen() because unlike strlen(), isset() is a language construct and not a function meaning that it's execution does not require function lookups and lowercase. This means you have virtually no overhead on top of the actual code that determines the string's length.

2) 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.

3) When it comes to printing text to screen PHP has so many methodologies to do it, not many users even know all of them. This tends to result in people using output methods they are already familiar from other languages. While this is certainly an understandable approach it is often not best one as far as performance in concerned.

print vs echo

Even both of these output mechanism are language constructs, if you benchmark the two you will quickly discover that print() is slower then echo(). The reason for that is quite simple, print function will return a status indicating if it was successful or not, while echo simply print the text and nothing more. Since in most cases (haven't seen one yet) this status is not necessary and is almost never used it is pointless and simply adds unnecessary overhead.

printf

Using printf() is slow for multitude of reasons and I would strongly discourage it's usage unless you absolutely need to use the functionality this function offers. Unlike print and echo printf() is a function with associated function execution overhead. More over printf() is designed to support various formatting schemes that for the most part are not needed in a language that is typeless and will automatically do the necessary type conversions. To handle formatting printf() needs to scan the specified string for special formatting code that are to be replaced with variables. As you can probably imagine that is quite slow and rather inefficient.

heredoc

This output method comes to PHP from PERL and like most features adopted from other languages it's not very friendly as far as performance is concerned. While this method allows you to easily output large chunks of text while preserving things like newlines and even allow for variable handling inside the text block this is quite slow and there are better ways to do that. Performance wise this is just marginally faster then printf() however it does not offer nearly as much functionality.

?> <?

When you need to output a large or even a medium sized static bit of text it is faster and simpler to put it outside the of PHP. This will make the PHP's parser effectively skipover this bit of text and output it as is without any overhead. You should be careful however and not use this for many small strings in between PHP code as multiple context switches between PHP and plain text will ebb away at the performance gained by not having PHP print the text via one of it's functions or constructs.

4) Many scripts tend to reply on regular expression to validate the input specified by user. While validating input is a superb idea, doing so via regular expression can be quite slow. In many cases the process of validation merely involved checking the source string against a certain character list such as A-Z or 0-9, etc... Instead of using regex in many instances you can instead use the ctype extension (enabled by default since PHP 4.2.0) to do the same. The ctype extension offers a series of function wrappers around C's is*() function that check whether a particular character is within a certain range. Unlike the C function that can only work a character at a time, PHP function can operate on entire strings and are far faster then equivalent regular expressions.
Ex.
preg_match("![0-9]+!", $foo);
vs
ctype_digit($foo);

5) Another common operation in PHP scripts is array searching. This process can be quite slow as regular search mechanism such as in_array() or manuall implementation work by itterating through the entire array. This can be quite a performance hit if you are searching through a large array or need to perform the searches frequently. So what can you do? Well, you can do a trick that relies upon the way that Zend Engine stores array data. Internally arrays are stored inside hash tables when they array element (key) is the key of the hashtables used to find the data and result is the value associated with that key. Since hashtable lookups are quite fast, you can simplify array searching by making the data you intend to search through the key of the array, then searching for the data is as simple as $value = isset($foo[$bar])) ? $foo[$bar] : NULL;. This searching mechanism is way faster then manual array iteration, even though having string keys maybe more memory intensive then using simple numeric keys.

Ex.

$keys = array("apples", "oranges", "mangoes", "tomatoes", "pickles");
if (in_array('mangoes', $keys)) { ... }

vs

$keys = array("apples" => 1, "oranges" => 1, "mangoes" => 1, "tomatoes" => 1, "pickles" => 1);
if (isset($keys['mangoes'])) { ... }

The bottom search mechanism is roughly 3 times faster.

If you know or have any additional optimization tricks let me know

#1 By sirisak on 2010-09-06 09:17

sirisak View my profile