our $hash = { 'a' => 'A', 'b' => 'B'};

our $y = 'bob';

cmpthese(-10, {
    'hash' => sub { for my $x (qw(a b a b a b)) { my $y = { 'a' => 'A', 'b' => 'B'}->{$x}; }},
    'ref' => sub { for my $x (qw(a b a b a b)) { my $y = $hash->{$x}; }},
});