#!/usr/bin/perl -w

use strict;
use Benchmark qw(timethese);

my @data = ("sponge\n","\n",
   "wibble\n","boing\n",
   "spam\n","\n"," spud\n"); 

my $nsre = qr/\S/;
my $isre = qr/^\s+$/;

timethese(1E6, {
   'nospace' => sub { grep {/$nsre/} @data; },
   'isspace' => sub { grep {!/$isre/} @data; }})