Very simple performance comparison - arrays vs objects (PHP 5.3.6)

gistfile1.sh

# php -v
PHP 5.3.6 (cli) (built: Mar 17 2011 20:58:15)
Copyright (c) 1997-2011 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies

# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
655040

# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $o = new ArrayObject; $o->name = "Adam";  $o->age = 35;  $s[] = $o;} echo memory_get_peak_usage(); ' | php
887984

# time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $o = new ArrayObject; $o->name = "Adam";  $o->age = 35;  $s[] = $o;} echo memory_get_peak_usage(); ' | php
61010784
real    0m1.448s
user    0m1.208s
sys     0m0.231s

# time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
33647944
real    0m0.525s
user    0m0.429s
sys     0m0.092s

Thanks! I need this test to find out which approach is better for my codes: array or stdobject.

In php > 5.4, this is completely different. See https://gist.github.com/nikic/5015323

From PHP 5.6.12

# php -v
PHP 5.6.12 (cli) (built: Aug  6 2015 17:14:56) 
Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies

### PHP Array memory usage ###
# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
807336

### PHP ArrayObject() memory usage (no properties defined) ###
# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $o = new ArrayObject; $o->name = "Adam";  $o->age = 35;  $s[] = $o;} echo memory_get_peak_usage(); ' | php
1144440

### PHP MyArrayObject() memory usage (properties defined) ###
# echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<1000;$x++){ $o = new MyArrayObject( 'Adam', 35 );  $s[] = $o;} echo memory_get_peak_usage(); ' | php
583600


### PHP Array memory usage + time (no properties defined) ###
# time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
58871792
real    0m0.193s
user    0m0.087s
sys 0m0.107s

### PHP ArrayObject() memory usage + time (no properties defined) ###
# time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $o = new ArrayObject; $o->name = "Adam";  $o->age = 35;  $s[] = $o;} echo memory_get_peak_usage(); ' | php
100801296
real    0m0.320s
user    0m0.153s
sys 0m0.163s

### PHP MyArrayObject() memory usage + time (properties defined) ###
# time echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<100000;$x++){ $o = new MyArrayObject( 'Adam', 35 );  $s[] = $o;} echo memory_get_peak_usage(); ' | php
44004544
real    0m2.209s
user    0m1.007s
sys 0m1.190s

We can conclude the following at least in PHP 5.6:

• Winner for Speed: Arrays are faster than objects (with undefined or defined properties)
• Winner for Memory: Objects with defined properties use less memory, 50%+ less than objects with undefined properties, only slightly less than Arrays

Ordered Fastest to Slowest in Speed for 100,000 items:

• 0.107s - Arrays
• 0.163s - Objects with undefined properties
• 1.190s - Objects with defined properties

Ordered Least to Most Memory Usage for 1,000 items:

• ~583kb - Objects with defined properties
• ~807kb - Arrays
• ~1.1mb - Objects with undefined properties

I ran these from Mac OSX terminal with local PHP, so the speeds aren't going to be the same as on a real server with ongoing load.

You can sometimes create your own symbol tables for arrays as well.

PHP 5.6

php -v
PHP 5.6.14-0+deb8u1 (cli) (built: Oct 4 2015 16:13:10)
Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies

echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
804616

echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $o = new ArrayObject; $o->name = "Adam"; $o->age = 35; $s[] = $o;} echo memory_get_peak_usage(); ' | php
1141704

echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<1000;$x++){ $o = new MyArrayObject("Adam", 35 ); $s[] = $o;} echo memory_get_peak_usage(); ' | php
545176

time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $s[] = array("name"=>"Adam","age"=>35); } echo memory_get_peak_usage(); ' | php
58869048

Timing	#1	#2	#3	#4	#5
real	0m0.385s	0m0.383s	0m0.384s	0m0.383s	0m0.385s
user	0m0.272s	0m0.276s	0m0.288s	0m0.312s	0m0.304s
sys	0m0.112s	0m0.104s	0m0.092s	0m0.072s	0m0.080s

time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $o = new ArrayObject; $o->name = "Adam"; $o->age = 35; $s[] = $o;} echo memory_get_peak_usage(); ' | php
100798560

Timing	#1	#2	#3	#4	#5
real	0m0.672s	0m0.666s	0m0.658s	0m0.662s	0m0.683s
user	0m0.524s	0m0.540s	0m0.544s	0m0.548s	0m0.540s
sys	0m0.144s	0m0.124s	0m0.116s	0m0.112s	0m0.140s

$ time echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<100000;$x++){ $o = new MyArrayObject("Adam", 35 ); $s[] = $o;} echo memory_get_peak_usage(); ' | php
40797616

Timing	#1	#2	#3	#4	#5
real	0m0.451s	0m0.464s	0m0.453s	0m0.471s	0m0.461s
user	0m0.368s	0m0.404s	0m0.396s	0m0.416s	0m0.388s
sys	0m0.084s	0m0.060s	0m0.056s	0m0.052s	0m0.072s

PHP 7.0

php -v
PHP 7.0.2-1~dotdeb+8.1 (cli) ( NTS )
Copyright (c) 1997-2015 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2015 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies

echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
760288

echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $o = new ArrayObject; $o->name = "Adam"; $o->age = 35; $s[] = $o;} echo memory_get_peak_usage(); ' | php
944248

echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<1000;$x++){ $o = new MyArrayObject("Adam", 35 ); $s[] = $o;} echo memory_get_peak_usage(); ' | php
465440

time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $s[] = array("name"=>"Adam","age"=>35); } echo memory_get_peak_usage(); ' | php
42145848

Timing	#1	#2	#3	#4	#5
real	0m0.203s	0m0.193s	0m0.201s	0m0.200s	0m0.193s
user	0m0.136s	0m0.144s	0m0.148s	0m0.164s	0m0.140s
sys	0m0.068s	0m0.052s	0m0.056s	0m0.040s	0m0.064s

time echo '<?php $s = array(); for($x=0;$x<100000;$x++){ $o = new ArrayObject; $o->name = "Adam"; $o->age = 35; $s[] = $o;} echo memory_get_peak_usage(); ' | php
61586192

Timing	#1	#2	#3	#4	#5
real	0m0.306s	0m0.288s	0m0.297s	0m0.309s	0m0.315s
user	0m0.236s	0m0.236s	0m0.256s	0m0.268s	0m0.244s
sys	0m0.072s	0m0.056s	0m0.044s	0m0.044s	0m0.072s

time echo '<?php $s = array(); class MyArrayObject{ public $name, $age; public function __construct( $name, $age ) { $this->name = $name; $this->age = $age; } } for( $x=0;$x<100000;$x++){ $o = new MyArrayObject("Adam", 35 ); $s[] = $o;} echo memory_get_peak_usage(); ' | php
13587384

Timing	#1	#2	#3	#4	#5
real	0m0.212s	0m0.221s	0m0.237s	0m0.238s	0m0.217s
user	0m0.180s	0m0.172s	0m0.192s	0m0.180s	0m0.188s
sys	0m0.032s	0m0.044s	0m0.052s	0m0.056s	0m0.028s

https://3v4l.org/30jdF/perf#tabs
https://3v4l.org/Qvl4W/perf#tabs
https://3v4l.org/DQ5jG/perf#tabs

For information, you will get very different results if each Array/Object is different :
Array("name"=>"Adam$x","age"=>$x)
MyArrayObject("Adam$x", $x)

A quick test for PHP 7.2 https://gist.github.com/charrondev/be56ef53e0408b959eff6d2d911e8c1e

Type	Memory Usage	Real execution Time
Arrays	46,191,568	0m0.137s
Classes	20,537,808	0m0.129s