I think you're not understanding what references do. In your example, you are not comparing slinging a bunch of data around vs. using a reference, you are comparing directly accessing a lexical variable vs. de-referencing the same variable and then accessing. I would expect the de-ref to always be slower.

There are tons of reasons to use references, but if you want to see the speed advantages of them, bench something like this:

#!/usr/bin/perl -w

use Benchmark;

my @array;
for (0..1000) {
  $array[$_] = rand(1000);
}

timethese(200, {
         'ref'       => sub {
           my @unsorted = @array;
           my $return_ref = sort_array_ref(\@unsorted);
         },
         'old skool' => sub {
           my @unsorted = @array;
           my @return_array = sort_array(@unsorted);
         },
        });

sub sort_array_ref {
  my $array_ref = shift;
  my @sorted_array = sort @{$array_ref};
  return \@sorted_array;
}

sub sort_array {
  my @array = @_;
  my @sorted_array = sort @array;
  return @sorted_array;
}

__END__
Benchmark: timing 200 iterations of old skool, ref...
 old skool:  6 wallclock secs ( 5.81 usr +  0.01 sys =  5.82 CPU) @ 34
+.36/s (n=200)
       ref:  6 wallclock secs ( 5.07 usr +  0.01 sys =  5.08 CPU) @ 39
+.37/s (n=200)
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