use Benchmark 'cmpthese';

my @list = 1 .. 1_000_000;
$result = 0;
cmpthese( 0, {
    list => sub { sub { $result = scalar @_ }->(   @list ) },
    refr => sub { sub { $result = scalar @_ }->( \ @list ) } } );
#          Rate     list     refr
# list   20.2/s       --    -100%
# refr 796087/s 3947995%       --