use Benchmark qw(:all) ;
cmpthese(20000, {
  readdir => sub { opendir my $fd, "."; my @files = readdir $fd; closedir $fd; },
  glob    => sub { my @files = (<*>,<.*>); }
});
__END__
           Rate    glob readdir
glob     3170/s      --    -75%
readdir 12739/s    302%      --