问在php函数中引用变量是否有助于节省内存？

EN

$hello = 'hello';

my_echo($hello);

//Better or worse than
my_echo_ref($hello);

//case 1, no referencing:
function my_echo($word) {
 echo $word;
} 

//case 2, referencing:
function my_echo_ref(&$word) {
  echo $word;
}