my @sorted=map substr($_,4),
      sort map pack(N => (stat)[9]) . $_, @files;

##</code><code>##

my $len=length pack I => 1;
my @sorted=map substr($_,$len),
      sort map pack(I => (stat)[9]) . $_, @files;

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use Benchmark qw/:all :hireswallclock/;

map substr($_,4),
  sort map pack(N => stat) . $_, @_;

my @files=glob '*';
my %time=map {$_ => (stat)[9]} @files;

sub spack { 
    map substr($_,4),
      sort map pack(N => $time{$_}) . $_, @_;
}

sub sprf1 { 
    map substr($_,10),
      sort map sprintf('%010u' => $time{$_}) . $_, @_;
}

sub sprf2 { 
    map substr($_,8),
      sort map sprintf('%08x' => $time{$_}) . $_, @_;
}

sub chk {
    my @a=(0,@_);
    shift @a <= $_ or return for @_;
    1;
}

my @sub=qw/spack sprf1 sprf2/;

for (@sub) {
    no strict 'refs';
    chk map $time{$_}, &{$_}(@files) or
      die "Error with sub '$_'\n";
}

cmpthese -30, { map { $_ => "$_(\@files)" } @sub };

__END__

##</code><code>##

          Rate sprf2 sprf1 spack
sprf2 756078/s    --   -7%  -24%
sprf1 811970/s    7%    --  -18%
spack 991485/s   31%   22%    --

##</code><code>##

       Rate sprf2 sprf1 spack
sprf2 319/s    --   -6%  -21%
sprf1 340/s    6%    --  -16%
spack 403/s   26%   19%    --