While arguably being less clear this method is faster by roughly a factor of roughly 3.5 (At least on the box I used to test)
$foo = array(
1 => "Value1",
2 => "Value2",
10 => "Value10"
);
while($bar = each($foo)){
echo $bar[0] . " => " . $bar[1];
}
I would imagine that this is due to the fact the foreach copies the entire array before iterating over it.