theme_links: $output and $num_links optimization ?

In includes/theme.inc, theme_links() is declared that way:

function theme_links($variables) {

  // [...]

  $output = '';

  if (count($links) > 0) {
    $output = '';

    // [...]

    $num_links = count($links);

    // [...]

  }
}

Wouldn't it be (a bit) more efficient to:
- remove the second $output=''; ?
- move $num_links = count($links); before the if statement and use it there ?

Result:

function theme_links($variables) {

  // [...]

  $output = '';

  $num_links = count($links);

  if ($num_links > 0) {

    // [...]

  }
}