43 Tips Mengoptimalkan Kode Script PHP

Here is the list of 43 short tips you can use for writing an optimized and more efficient PHP code:

  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. Use echo's multiple parameters instead of string concatenation.
  4. Set the maxvalue for your for-loops before and not in the loop.
  5. Unset your variables to free memory, especially large arrays.
  6. Avoid magic like __get, __set, __autoload
  7. require_once()

    is expensive
  8. Use full paths in includes and requires, less time spent on resolving the OS paths.
  9. If you need to find out the time when the script started executing,

    @import url("css/widgContent.css");

    INSERT:CONTENT:END SERVER['REQUEST_TIME'] is preferred to

    time()

  10. See if you can use strncasecmp, strpbrk and stripos instead of regex
  11. str_replace

    is faster than

    preg_replace

    , but

    strtr

    is faster than

    str_replace

    by a factor of 4
  12. If the function, such as string replacement function, acceptsboth arrays and single characters as arguments, and if your argumentlist is not too long, consider writing a few redundant replacementstatements, passing one character at a time, instead of one line ofcode that accepts arrays as search and replace arguments.
  13. It's better to use select statements than multi if, else if, statements.
  14. Error suppression with @ is very slow.
  15. Turn on apache's mod_deflate
  16. Close your database connections when you're done with them
  17. $row['id']

    is 7 times faster than

    $row[id]

  18. Error messages are expensive
  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.
  20. Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function.
  21. Incrementing a global variable is 2 times slow than a local var.
  22. Incrementing an object property (eg.

    $this->prop++

    ) is 3 times slower than a local variable.
  23. Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one.
  24. Just declaring a global variable without using it in afunction also slows things down (by about the same amount asincrementing a local var). PHP probably does a check to see if theglobal exists.
  25. Method invocation appears to be independent of the number ofmethods defined in the class because I added 10 more methods to thetest class (before and after the test method) with no change inperformance.
  26. Methods in derived classes run faster than ones defined in the base class.
  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.
  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.
  29. When echoing strings it's faster to separate them by commainstead of dot. Note: This only works with echo, which is a functionthat can take several strings as arguments.
  30. A PHP script will be served at least 2-10 times slower thana static HTML page by Apache. Try to use more static HTML pages andfewer scripts.
  31. Your PHP scripts are recompiled every time unless thescripts are cached. Install a PHP caching product to typically increaseperformance by 25-100% by removing compile times.
  32. Cache as much as possible. Use memcached - memcached is ahigh-performance memory object caching system intended to speed updynamic web applications by alleviating database load. OP code cachesare useful so that your script does not have to be compiled on everyrequest
  33. When working with strings and you need to check that thestring is either of a certain length you'd understandably would want touse the strlen() function. This function is pretty quick since it'soperation does not perform any calculation but merely return thealready known length of a string available in the zval structure(internal C struct used to store variables in PHP). However becausestrlen() is a function it is still somewhat slow because the functioncall requires several operations such as lowercase & hashtablelookup followed by the execution of said function. In some instance youcan improve the speed of your code by using an isset() trick.

    Example:

    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() becauseunlike strlen(), isset() is a language construct and not a functionmeaning that it's execution does not require function lookups andlowercase. This means you have virtually no overhead on top of theactual code that determines the string's length.

  34. 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 suddenlybecome 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 ofa temporary var that is then incremented. While pre-incrementationincreases the original value directly. This is one of the optimizationthat opcode optimized like Zend's PHP optimizer. It is a still a goodidea to keep in mind since not all opcode optimizers perform thisoptimization and there are plenty of ISPs and servers running withoutan opcode optimizer.
  35. Not everything has to be OOP, often it is too much overhead, each method and object call consumes a lot of memory.
  36. Do not implement every data structure as a class, arrays are useful, too
  37. Don't split methods too much, think, which code you will really re-use
  38. You can always split the code of a method later, when needed
  39. Make use of the countless predefined functions
  40. If you have very time consuming functions in your code, consider writing them as C extensions
  41. Profile your code. A profiler shows you, which parts of yourcode consumes how many time. The Xdebug debugger already contains aprofiler. Profiling shows you the bottlenecks in overview
  42. mod_gzip which is available as an Apache module compresses your data on the fly and can reduce the data to transfer up to 80%
  43. Excellent Article about optimizing php by John Lim

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