use warnings;
use strict;
use Benchmark qw/cmpthese/;
sub foo { 1+2==3 }
cmpthese(1e8, {
    one => \&foo,
    two => sub { foo() },
});

__END__

          Rate  two  one
two 24271845/s   -- -72%
one 86956522/s 258%   --