15 Tips to Optimize Your PHP Script for Better Performance for Developers

by Luke P. Issac on April 1, 2014

If you are a developer, it is essential for you to optimize your script early in the development process itself. Following the best practices while coding your PHP script is a good starting point to write a well optimized PHP code.

This tutorial provides few tips to optimize PHP code from a developer point of view.

1. Use Native PHP Functions

As much as possible, try to use native PHP functions rather than writing your own functions to achieve the objective. For example, you can use range( b, k) to get an array of alphabets starting from b to k in sequence, if it is only needed once in the script rather than declaring an array with these values in a function and returning it on its call.

2. Use Single Quotes

Using single quotes ( ‘ ‘ ) is faster than using double quotes( ” ” ) if you are going to keep only the string inside it avoiding any variables. Double quotes checks for the presence of variable and adds little bit of overhead.

3. Use = = =

Use “= = =” instead of “= =”, as the former strictly checks for a closed range which makes it faster.

4. Use Appropriate Str Functions

str_replace is faster than preg_replace, but strtr is faster than str_replace by a factor of 4.

5. Calculate Only Once

Calculate and assign the value to the variable if that value is getting used numerous time rather than calculating it again and again where it is being used.

For example, the following will degrade the performance.

for( $i=0; i< count($arrA); $i++){
  echo count($arrA);
}

The script below will perform much better.

$len = count($arrA);
for( $i=0; i< $len; $i++){
  echo $len;
}

6. Pass Reference to Function

Pass reference to the function if it does not affect your logic. A function manipulating the reference is faster than those manipulating the value been passed as here one more copy of the value is getting created. Especially it adds overhead when the value passed by you is a big array.

For example, let us create a function in two different way to increment by 1, each element of an array having values 0 to 99.

<?php
  // passing by reference
  function  computeValue( &$param ){
  	// Something goes here
  	foreach( $param as $k => $value){
  	  $param[$k] = $value + 1;
  	}
  }
  $x = array();
  for( $i =0; $i<99; $i++){
    $x[$i] = $i;
  }
  computeValue( $x);
  
  // array with 100 elements each incremented by 1
  print_r( $x );

?>                   		 

The function above works faster than the function below although both will produce the same result ( increment each element of the array by 1. )

  <?php
  	// passing by value
    function  computeValue( $param ){
      // Something goes here
      foreach( $param as $k => $value){
      	$param[$k] = $value + 1;
      }
      
      return $param;
    }
    $x = array();
    for( $i =0; $i<99; $i++){
      $x[$i] = $i;
    }
	// array with 100 elements each incremented by 1
    print_r(computeValue( $x));
    
  ?>

7. Create Classes Only When its Required

Don’t create classes and method until and unless its really needed, used and reused as well.

8. Disable Debugging Messages

File operations are expensive. So, if you have written lot of custom functions to log errors and warning during your development process, make sure you remove them before you push the code to production.

9. Use Caching Techniques

Use cache to reduce the load of database operations as well as the script compilation. We can use memcache for the reducing database load and APC for opcode caching and intermediate code optimization.

10. Close the Connection

Get into the habit to unset the variables and close database connection in your PHP code. It saves memory.

11. Reduce Number of Hits to DB

Try to reduce the number of hits to the database. Make queries aggregate so that you call the database less number of times. For example:

<?php
  $con=mysqli_connect("localhost","username","somepassword","anydb");
  
  if (mysqli_connect_errno())
  {
    echo "Failed to connect to MySQL" ;
	mysqli_connect_error(); 
  }

  function insertValue( $val ){
    mysqli_query($con,"INSERT INTO tableX (someInteger) VALUES ( $val )");
  }
  
  for( $i =0; $i<99; $i++){
    //  Calling function to execute query one by one 
    insertValue( $i );
  }					
  // Closing the connection as best practice		
  mysqli_close($con);

?> 

The script above is much slower than the script below:

<?php
  $con=mysqli_connect("localhost","username","somepassword","anydb");
  if (mysqli_connect_errno())
  {
  	echo "Failed to connect to MySQL" ;
  	mysqli_connect_error(); 
  }
   
  function insertValues( $val ){
     // Creating query for inserting complete array in single execution.
    $query= " INSERT INTO tableX(someInteger) VALUES .implode(',', $val)";      
    mysqli_query($con, $query);
  }
  
  $data = array();
  for( $i =0; $i<99; $i++){
    // Creating an array of data to be inserted.
    $data[ ]  =   '(" ' . $i. '")' ;
  }
  // Inserting the data in a single call
  insertValues( $data );
  // Closing the connection as a best practice
  mysqli_close($con);

?> 

12. Frequently Used Switch Cases

Keep most frequently used switch cases on the top.

13. Use Methods in Derived Classes

Methods in derived classes are faster than base classes. For example, let there be a function in both base class and derived class for performing task1. It is named as “forTask1″ in base class and “forTask1again” in derived class, so that they will not override.

Call to the function “forTask1again( )” which is in derived class will work faster than call to the function “forTask1( )” as it is from base class.

<?php
  class someBaseClass
  {
  	public function forTask1($string)
  	{
  		// perform task 1
  	}
  	public function forTask2( )
  	{
  		// perform task 2
  	}
  }
  
  class derivedClass extends someBaseClass
  {
  	public function forTask1again($string)
  	{
  		//perform task 1 same as the function in base class.
  	}
  	public function forTask3($string)
  	{
  		//perform task 3
  	}
  }
  //Instantiating the derived class below.
  $objDerivedClass = new derivedClass( ); 
  
  // The call below works slow for task1 as it is from base class.
  $resultTask1 = $objDerivedClass->forTask1( );
  
  // The call below works faster for task1 as 
  // it is from derived class.
  $sameResultTask1 = $objDerivedClass->forTask1again();
?>

14. Use JSON

Use JSON instead of XML while working with web services as there are native php function like json_encode( ) and json_decode( ) which are very fast. If you are bound to have XML form of data, then use regular expression to parse it instead of DOM manipulation.

15. Use isset

Use isset( ) where ever possible instead of using count( ), strlen( ), sizeof( ) to check whether the value returned is greater than 0.

For example, let us assume that you have a function which returns an array with values or a NULL array. Now you want to check whether the returned array is with values or not, then use the following:

if(isset($returnValue)){
  // do something here
}

In this case, use the above code block, instead of the following:

if(count($returnValue) > 0){
  // do something here
}

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{ 13 comments… read them below or add one }

1 Haruni April 2, 2014 at 12:45 am

Thank you!
It helped a lots, keep doing great job.

2 Tariq Aziz April 2, 2014 at 1:08 am

Its really fruitful and should i say that not only in PHP but generally for all languages these would apply. Especially Calculate once is a thing is highly logical in context of efficient coding delivering performance.

3 SMAHI April 2, 2014 at 1:19 am

Thank you very much.

4 Mukesh April 2, 2014 at 2:52 am

Very helpful tips! Thanks for the article.

5 Rod Elias April 2, 2014 at 9:22 pm

Thanks for such valuable tips.
Please keep posting more stuff about PHP.
Hugs!

6 Pratik April 7, 2014 at 5:14 am

Thank you very much Ramesh

7 Dustin April 7, 2014 at 8:12 am

As to tip #9, I couldn’t agree more. As of php 5.5 OPcache is included by default and works extremely well. It stores precompiled script bytecode in shared memory so scripts don’t have to be parsed each time a page is requested.

8 Dave April 9, 2014 at 1:17 am

“If you are bound to have XML form of data, then use regular expression to parse it instead of DOM manipulation.”

I have to disagree here. Regular expressions are used to parse regular languages whereas XML is a markup language. Simplexml or other xml parsing method is the proper way.

9 Robin April 19, 2014 at 10:41 am

But unfortunately, Simple xml and other xml parsing methods are very slow than using a Regular expression, because simplexml and other xml parsers mostly need the complete xml to be loaded and then create the node structure, which adds a huge overheads.
On the other hand if you are an expert in using regular expression, using it will eliminate this overhead in most cases.
We can use regular expression to parse xml, if performance is at highest priority rather than standards and simplicity to script it.

10 Mike Dinescu May 2, 2014 at 8:45 am

While there is nothing wrong with following best practices and understanding performance implications of constructs and idioms in a language I disagree with the directive to optimize early. Premature optimization can have disastrous consequences to the quality of code as well as to the overall scalability of the code base.

DO use a profiler!
DO optimize when necessary!
DO measure/test often!

DON’T just blindly “optimize” code as you write it!

11 Jalal Hajigholamali May 2, 2014 at 9:08 pm

Hi,

Thank you,

very useful article

12 Anonymous May 9, 2014 at 7:52 am

tip #13 go against OOP principles and code maintenance so i think is better to find a good way between performance, maintenace and reusability

13 crossRT July 3, 2014 at 10:06 am

Thank you for the tips! it’s very useful!
But anyone can further explain about tips 12 frequently used switch cases? why?

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