You're not testing what you claim you're testing: you're testing creating and accessing an an anonymous hash vs only accessing a named hash. You're also reading the result the wrong way 'round.

use strict;
use warnings;
use Benchmark qw(cmpthese);

cmpthese(-10, {
    'anon' => sub { for my $x (qw(a b a b a b)) { my $y = { 'a' => 'A'
+, 'b' => 'B'}->{$x}; }},
    'named' => sub { for my $x (qw(a b a b a b)) { my $h = { 'a' => 'A
+', 'b' => 'B'}; my $y = $h->{$x}; }},
});
[download]

output:

         Rate named  anon
named 78120/s    --   -8%
anon  84539/s    8%    --
[download]

Meaning that using an anonymous (not stored) hash is just a bit faster. Not very interesting, considering you almost always want to reuse a hash you've just created.

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