Recursive function: multidimensional array looping through 3 x faster

A faster way to replace the strings in multidimensional array is to json_encode() it, do the str_replace() and then json_decode() it, like this: 

<?php function str_replace_json($search, $replace, $subject){
     return json_decode(str_replace($search, $replace,  json_encode($subject)));

} ?> 
This method is almost 3x faster (in 10000 runs.) than using recursive calling and looping method, and 10x simpler in coding. 

Compared to: 

<?php function str_replace_deep($search, $replace, $subject)
{
    if (is_array($subject))
    {
        foreach($subject as &$oneSubject)
            $oneSubject = str_replace_deep($search, $replace, $oneSubject);
        unset($oneSubject);
        return $subject;
    } else {
        return str_replace($search, $replace, $subject);
    }
} ?>