use Benchmark qw(cmpthese);

use strict;
use warnings;

$\="\n";

cmpthese 1000000, {
  empty_strings => sub {
    my %h = (
      shave  => '',
      the    => '',
      modern => '',
      way    => '',
    );
    my $mod = defined $h{modern};
    my $ant = not defined $h{antique};
    our $went_empty;
    print( ($mod?'y':'n'), ', ', ($ant?'y':'n') ) unless $went_empty++
+;
  },
  ones => sub {
    my %h = (
      shave  => 1,
      the    => 1,
      modern => 1,
      way    => 1,
    );
    my $mod = $h{modern};
    my $ant = not $h{antique};
    our $went_one;
    print( ($mod?'y':'n'), ', ', ($ant?'y':'n') ) unless $went_one++;
  },
  undefs => sub {
    my %h = (
      shave  => undef,
      the    => undef,
      modern => undef,
      way    => undef,
    );
    my $mod = exists $h{modern};
    my $ant = not exists $h{antique};
    our $went_undef;
    print( ($mod?'y':'n'), ', ', ($ant?'y':'n') ) unless $went_undef++
+;
  },
  one_big_undef => sub {
    my %h;
    undef @h{qw{shave the modern way}};
    my $mod = exists $h{modern};
    my $ant = not exists $h{antique};
    our $went_big;
    print( ($mod?'y':'n'), ', ', ($ant?'y':'n') ) unless $went_big++;
  }
}
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y, y
y, y
y, y
y, y
                  Rate empty_strings          ones        undefs one_big_undef
empty_strings 319489/s            --          -18%          -20%          -29%
ones          390625/s           22%            --           -2%          -14%
undefs        398406/s           25%            2%            --          -12%
one_big_undef 452489/s           42%           16%           14%            --