#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw(cmpthese);
use Socket qw(inet_aton inet_ntoa);

chomp( my @ips=(<>) );

cmpthese(-10,
    {
        inet_grt => sub { 
            my @sorted = map { inet_ntoa $_ }
                sort { $a cmp $b }
                map { inet_aton $_ } @ips;
        },
        inet_grt2 => sub { 
            my @sorted = map { unpack 'x4A*' }
                sort { $a cmp $b }
                map { pack('A4A*', inet_aton($_), $_) } @ips;
        },
        inet_orc => sub { 
            my @sorted = sort by_ip @ips;
        },
        splitwise => sub {
            my @sorted =
            map $_->[0],
            sort {
                $a->[1] <=> $b->[1] or
                $a->[2] <=> $b->[2] or
                $a->[3] <=> $b->[3] or
                $a->[4] <=> $b->[4]
            }
            map [$_, split /\./], @ips;
        },
        split_int => sub {
            my @sorted = map { join '.', unpack("CCCC", pack("N",$_)) 
+}
                sort { $a <=> $b }
                map { unpack("N",pack("CCCC",split /\./)) } @ips;
        },
        naive => sub {
            my @sorted = sort {
                my @a = split /\./, $a;
                my @b = split /\./, $b;
                $a[0] <=> $b[0] or
                $a[1] <=> $b[1] or
                $a[2] <=> $b[2] or
                $a[3] <=> $b[3]
                } @ips;
        },
    });

{
    my %cache;
    sub by_ip
    {
        my $orc_a = ($cache{$a} ||= inet_aton($a));
        my $orc_b = ($cache{$b} ||= inet_aton($b));
        $orc_a cmp $orc_b;
    }
}

__END__
            Rate     naive split_int splitwise  inet_orc inet_grt2  in
+et_grt
naive     8.65/s        --      -86%      -88%      -89%      -93%    
+  -96%
split_int 62.5/s      622%        --      -12%      -17%      -52%    
+  -69%
splitwise 71.1/s      722%       14%        --       -6%      -45%    
+  -65%
inet_orc  75.4/s      772%       21%        6%        --      -42%    
+  -63%
inet_grt2  129/s     1393%      107%       82%       71%        --    
+  -36%
inet_grt   201/s     2229%      222%      183%      167%       56%    
+    --
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My input was a list of 1000 random IP addresses generated by nmap, listed in the HTML comments for this node