use Benchmark qw(cmpthese);

sub rbyte { int rand 256 }

my @unsorted;
for (1..10000) { push @unsorted, join '.', rbyte, rbyte, rbyte, rbyte }

sub sort_by_ip_address
{
  return sort { pack("C4",split(/\./,$a)) cmp pack("C4",split(/\./,$b)) } @_
}

sub sort_faster
{
  return map {$_->[1]} sort {$a->[0] cmp $b->[0]} map {[(pack('C4',split(/\./,$_))), $_]} @_
}

my @sorted;
cmpthese( 10, {
	'  slow' => sub { @sorted = sort_by_ip_address(@unsorted) },
	'faster' => sub { @sorted = sort_faster(@unsorted) },
});
__END__
$ perl fastip.pl 
Benchmark: timing 10 iterations of  slow, faster...
      slow: 80 wallclock secs (40.79 usr +  0.00 sys = 40.79 CPU) @  0.25/s (n=10)
    faster: 15 wallclock secs ( 6.95 usr +  0.06 sys =  7.01 CPU) @  1.43/s (n=10)
       s/iter   slow faster
  slow   4.08     --   -83%
faster  0.701   482%     --