Description:
------------
for short messages crc32 seems to be the fastest way but for long messages like a whole page content for a ETAG-HTTP-Header it's the slowest

md5:   0.48954606056213
sha1:  0.57872104644775
crc32: 0.64182901382446

that should not be the case on modern Intel CPUs like SnadyBrdige or newer which support a accelerated instruction



Test script:
---------------
$test_content = file_get_contents('global.inc.php', true);

echo '<strong>md5: </strong>' . md5($test_content) . MY_LE;
$profiler->reset();
for($x=1;$x<5000;$x++)
{
 $rw = md5($test_content);
}
echo $profiler->get() . '<br /><br />' .  MY_LE;

echo '<strong>sha1: </strong>' . sha1($test_content) . MY_LE;
$profiler->reset();
for($x=1;$x<5000;$x++)
{
 $rw = sha1($test_content);
}
echo $profiler->get() . '<br /><br />' .  MY_LE;

echo '<strong>crc32: </strong>' . abs(crc32($test_content)) . MY_LE;
$profiler->reset();
for($x=1;$x<5000;$x++)
{
 $rw = crc32($test_content);
}
echo $profiler->get() . '<br /><br />' .  MY_LE;