<?php

$array = array();
for ($index = 0; $index < 1000000; $index++) {
    $array[] = rand(0, 255);
}

$res = array();
for($index = 0; $index < 100; $index++){

    $start = microtime(TRUE);
    //echo "start: $start<br>\r\n";

    foreach ($array as $value) {
        $value = 5 * $value;
    }

    $p1 = microtime(TRUE);    
    //echo "No references: ".($p1 - $start)."<br>\r\n";

    foreach ($array as &$value2) {
        $value2 = 5 * $value2;
    }

    $p2 = microtime(TRUE);
    //echo "References: ".($p2 - $p1)."<br>\r\n";
    $res[] = array( 'noref' => $p1 - $start, 'ref' => $p2 - $p1);
}

$min1 = $min2 = 1000000;
$max1 = $max2 = 0;
$sum1 = $sum2 = 0;
foreach ($res as $value) {
    if($value['noref'] < $min1)
        $min1 = $value['noref'];
    if($value['noref'] > $max1)
        $max1 = $value['noref'];
    
    if($value['ref'] < $min2)
        $min2 = $value['ref'];
    if($value['ref'] > $max2)
        $max2 = $value['ref'];
    
    $sum1 += $value['noref'];
    $sum2 += $value['ref'];
}

$avg1 = $sum1 / count($res);
$avg2 = $sum2 / count($res);
$precent = ($avg2 - $avg1)*100/$avg1;

echo "Result: <br>\r\n Min: Noref = $min1, Ref = $min2 <br>\r\n Max: Noref = $max1, Ref = $max2 <br>\r\n Avg: Noref = $avg1, Ref = $avg2 <br>\r\n Precent: $precent";

?>