$values = array();

for ($i = 0; $i < 1000000; $i++) {
    $values[] = rand(0, 1000);
}

$max = 0;
$maxi = 0;
$n = 0;
$m = 59;
$sum = array_sum(array_slice($values, $n, $m));

for ($i = 0; $i < 999940; $i++) {
    $n++;
    $m++;

    if($sum > $max) {
        $maxi = $i;
        $max = $sum;
    }

    $sum = $sum + $values[$m] - $values[$n];
}

$maxValues = array_slice($values, $maxi, 60);