$dir = "test";

mkdir $dir or die "Unable to create dir : $!" if not ( -d "$dir");
chdir $dir;

foreach ( 'aaa' .. 'zzz' ) {
    open F, "> $_";
    my $data = chr(97 + int rand 10);
    print F $data;
    close F;
}

##</code><code>##

use Benchmark qw/cmpthese/;

$dir = "test";
opendir DIR, "< $dir";

cmpthese(1000, {
  'grep' => sub {
               opendir DIR, "$dir" or die "Unable to open dir : $!\n";
               @list=grep(!/^(\.+?)$/,readdir(DIR));
               closedir DIR;
            },
  'while' => sub {
               opendir DIR, "$dir" or die "Unable to open dir : $!\n";
               while (readdir(DIR)) {
                 push @list, $_ unless /^(\.+?)$/;
               closedir DIR;
               }
             }
});

##</code><code>##

D:\Perl\bin>perl test2.pl
        Rate   grep  while
grep  6.51/s     --  -100%
while 2667/s 40833%     --

D:\Perl\bin>