Your benckmark is flawed.

The point to passing references is that you can group multiple things together. The return values and arguments to functions all go on the stack as a list. The less impact you have on this stack, the less pushing/popping work perl will have to do. Less work == faster. In your example you do not vary the number of parameters appropriately.

Smaller argument lists are faster

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%       --
[download]

Smaller return lists are faster

use Benchmark 'cmpthese';

@list = 1 .. 1_000_000;
@result = @list;
$result = \ @list;
cmpthese( 0, {
    list => sub { @result = sub {   @list }->() },
    refr => sub { $result = sub { \ @list }->() } } );
#          Rate      list      refr
# list   1.67/s        --     -100%
# refr 774198/s 46258208%        --
[download]