If "L" in "blob" stands for "large", and script is anything but a throw-away one-liner, I'd be unhappy about implicitly building large useless intermediate lists. 

use strict;
use warnings;
use feature 'say';
use Data::Dump 'dd';
use Benchmark 'cmpthese';

my $data = "1ABCD2EFGH3IJKL4MNOP5QRST6UVWX" x 1000;

cmpthese -3, {
    1 => sub {
        my @out;
        for ( my $x = 0; $x < length $data; $x += 5 ) {
            push @out, [ unpack "CA4", substr $data, $x, 5 ]
        }
        return \@out
    },
    2 => sub {
        [ map [ unpack 'CA4', $_ ], unpack "(A5)*", $data ]
    }
};

__END__

    Rate    2    1
2 34.2/s   -- -21%
1 43.1/s  26%   --

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In reply to Re: Perlish approach to parsing a binary blob by vr
in thread Perlish approach to parsing a binary blob by mxb

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