PHP string concatenation benchmarks. Run on a MacBook (2.4GHz Core 2 Duo, 2GB RAM) with PHP 5.3.2 (cli)

gistfile1.php

<?php
$str = '';
for ($i = 0; $i < 30000; $i++) {
	$str .= 'String concatenation. ';
}

/*****************************************
 0.061
 0.057
 0.063
 -----
 0.06
*****************************************/

gistfile2.php

<?php
$str = '';
for ($i = 0; $i < 30000; $i++) {
	$str = $str . 'String concatenation. ';
}

/*****************************************
 3.333
 3.348
 3.354
 -----
 3.35
*****************************************/

gistfile3.php

<?php
$str = '';
$sArr = array();
for ($i = 0; $i < 30000; $i++) {
	$sArr[] = 'String concatenation. ';
}
$str = implode($sArr);

/*****************************************
 0.092
 0.088
 0.089
 -----
 0.09
*****************************************/

gistfile4.php

<?php
$str = '';
for ($i = 0; $i < 30000; $i++, $str .= 'String concatenation. ');

/*****************************************
 0.063
 0.062
 0.066
 -----
 0.06
*****************************************/

gistfile5.php

<?php
$str = 'String concatenation. ';
$times = log(30000) / log(2);
for ($i = 0; $i < $times; $i++, $str .= $str);

/*****************************************
 0.059
 0.056
 0.058
 -----
 0.06

 This algorithm actually generates 32768 concatenations. It's not
 much faster on small sets, but is ideally suited for huge numbers
 of non-atomic concatenations -
   ~300,000 concatenations only take 0.08 seconds.
   ~3,000,000 concatenations take around 0.23 seconds.
*****************************************/