<?php

function print_mem($x = '-')
{
    print $x . " => " . memory_get_usage(false) . " - " .
          memory_get_peak_usage(false) . "\n";
}

function fit_it()
{
    $filename = "/a/long/text/file"; // /boot/config-2.6.22-14-generic
    $handle   = fopen($filename, "r");
    $contents = fread($handle, filesize($filename));
    fclose($handle);

    return $contents;
}

print_mem();

$a = fit_it();
print_mem("a");

$b = fit_it();
print_mem("b");

$c = $b;
print_mem("c");

$c .= 'a';
print_mem("c");

$d = &$b;
print_mem("d");