(Even for am Atom, your perl seems really, really slow. You have Moo running on your system at half the speed of Moose on mine?)

I have that also, but still not seeing the benefit :

C:\test>ppm-shell
ppm 4.10 (ActivePerl 1007)
Copyright (C) 2010 ActiveState Software Inc.  All rights reserved.
ppm> search Class::XSAccessor
1: Class-XSAccessor
   Generate fast XS accessors without runtime compilation
   Version: 1.13
   Released: 2011-12-12
   Author: Steffen Mueller <smueller@cpan.org>
   Provide: Class::XSAccessor version 1.13
   Provide: Class::XSAccessor::Array version 1.13
   Provide: Class::XSAccessor::Heavy version 1.13
   Require: XSLoader
   Repo: ActiveState Package Repository
   CPAN: http://search.cpan.org/dist/Class-XSAccessor-1.13/
   Installed: 1.13 (site)
ppm> quit


C:\test>perl -MClass::XSAccessor -E"say $Class::XSAccessor::VERSIO
1.13

C:\test>type junk99.pl
use Benchmark qw(cmpthese);

{
    package Foo1;
    sub new { bless $_[1], $_[0] }
    sub foo { $_[0]{foo} }
}

{
    package Foo2;
    use Moo;
    has foo => (is => 'ro');
}

{
    package Foo3;
    use Moose;
    has foo => (is => 'ro');
}

our $foo1 = Foo1::->new({foo => 0});
our $foo2 = Foo2::->new({foo => 0});
our $foo3 = Foo3::->new({foo => 0});
our $foo4 = { foo => 0 };

cmpthese( -3, {
    OO_perl     => q[ $foo1->foo for 1 .. 1000; ],
    moo         => q[ $foo2->foo for 1 .. 1000; ],
    moose       => q[ $foo3->foo for 1 .. 1000; ],
    plain_perl  => q[ $foo4->{foo} for 1 .. 1000; ],
});

C:\test>junk99
             Rate      moose        moo    OO_perl plain_perl
moose      1969/s         --        -4%       -17%       -74%
moo        2043/s         4%         --       -14%       -73%
OO_perl    2382/s        21%        17%         --       -69%
plain_perl 7624/s       287%       273%       220%         --
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