use strict;
use warnings;
use Benchmark qw/cmpthese/;

my @matrix = (
    [  1,  2,  3,  4,  5,  ],
    [  6,  7,  8,  9, 10,  ],
    [ 11, 12, 13, 14, 15,  ],
    [ 16, 17, 18, 19, 20,  ],
    [ 21, 22, 23, 24, 25,  ],
);

cmpthese(
    50000,
    {
        onemap  => sub{ my $result =  onemap( \@matrix ); },
        twomaps => sub{ my $result = twomaps( \@matrix ); },
    }
);

sub onemap {
    my $matrix = shift;
    return {
        Matrix => [
            map {
                [
                    @$_
                ]
            } @$matrix
        ]
    };
}

sub twomaps {
    my $matrix = shift;
    return {
        Matrix => [ 
            map { 
                my $row = $_; 
                [ 
                    map { ( $_ ); } @$row 
                ] 
            } @$matrix 
        ] 
    };
}

__END__
            Rate twomaps  onemap
twomaps  62814/s      --    -39%
onemap  103306/s     64%      --