Re: Wasting time thinking about wasted time

[Aristotle]

It's a lot longer and wouldn't fit on a slide

I don't see why it has to be. You can level the playing field without any significant difference.

use Benchmark qw( timethese );
my @files = glob "/bin/*";
timethese( -2, {
    Ordinary => sub {
        () = sort { -M $a <=> -M $b } @files
    },
    Schwartzian => sub {
        () = 
            map $_->[0],
            sort { $a->[1] <=> $b->[1] }
            map [ $_, -M ],
            @files;
        },
    },
);

And that's it. Note that I always use sub refs with Benchmark, so the package issues don't even come up. You could assign to an actual array if you don't feel like explaining the () = .. construct, but it wouldn't make an appreciable difference in the code.