Return Values Copied? Copied if By Reference?

Is a function return value copied? If the value is an integer I suppose it is but what about a string or an array? If you pass by reference is the return value still copied? For example, is this: function foo(&$arr) { $arr[] = "bar"; } faster than this? function foo(&$arr) { $arr[] = "bar"; return $arr; // is this copied? } I'm working on some code that would be called to generate a cell in a possibly large table and therefore a small difference in performance may have a significant impact. Thanks, Mike -- Michael B Allen PHP Extension for SSO w/ Windows Group Authorization http://www.ioplex.com/