Corrected

gistfile1.txt

<?php
require( 'src/Phifty/TaskTimer.php' );
use Phifty\TaskTimer;

$size = 1000;
echo "n=$size\n";
$timer = new TaskTimer;
$timer->start( 'pure php iteration' );

$list = range(1,1000);
for( $i = 0 ; $i < $size ; $i++ ) {
    $output = '';
    $output .= '[';
    $cnt = count($list);
    for( $j = 0 ; $j < $cnt ; $j++ ) {
        if( $j > 0 )
            $output .= ',';
        $output .= $list[ $j ];
    }
    $output .= ']';
}
$timer->end()->report();


$timer->start( 'via string join' );
for( $i = 0 ; $i < $size ; $i++ ) {
    $output = '[' . join(',',$list) . ']';
}
$timer->end()->report();


$timer->start( 'json_encode' );
for( $i = 0 ; $i < $size ; $i++ ) {
    $oiutput = json_encode( $list );
}
$timer->end()->report();