<?php
$test = array(
    array(
        'id' => 259,
        'value' => 13
    ),
    array(
        'id' => 258,
        'value' => 14
    )
);
$b = time();
for ($i = 0; $i < 100000000; $i++)
{
    $a = array();
    foreach ($test as $t)
        $a[] = $t['value'];
    $result = implode(',', $a);
}
$e = time();
var_dump($e-$b);
$b = time();
for ($i = 0; $i < 100000000; $i++)
{
    $result = implode(',', array_map(function($a) {return $a['value'];}, $test));
}
$e = time();
var_dump($e-$b);
$b = time();
for ($i = 0; $i < 10000000; $i++)
{
    $a = '';
    foreach ($test as $t)
        $a .= $t['value'] . ',';
    $result = rtrim($a, ',');
}
$e = time();
var_dump($e-$b);