Sure thing 

use Benchmark qw( cmpthese );

our $data = '0:13:46:b:4:31';

cmpthese(-3, {
   ike_orig => 'my $mac = $data; $mac =~ s/(^|:)(?=[0-9a-fA-F](?::|$))
+/${1}0/g;               $mac;',
   ike_fast => 'my $mac = $data; $mac =~ s/(?<=:)(?=[0-9a-fA-F](?::|$)
+)/0/g;
                                 $mac =~ s/^(?=[0-9a-fA-F](?::|$))/0/;
+                        $mac;',
   skeeve   => 'my $mac = $data; $mac = join ":", map substr("0$_",-2)
+, split/:/, $mac;       $mac;',
   jwkrahn1 => 'my $mac = $data; $mac =~ s/([^:]+)/ sprintf "%02s", $1
+ /eg;                   $mac;',
   jwkrahn2 => 'my $mac = $data; $mac = join ":", map sprintf( "%02s",
+ $_ ), split /:/, $mac; $mac;',
});

[download]
            Rate ike_orig jwkrahn1   skeeve jwkrahn2 ike_fast
ike_orig 37908/s       --      -3%     -29%     -31%     -43%
jwkrahn1 38957/s       3%       --     -27%     -29%     -41%
skeeve   53318/s      41%      37%       --      -3%     -20%
jwkrahn2 54879/s      45%      41%       3%       --     -18%
ike_fast 66551/s      76%      71%      25%      21%       --

[download]

In reply to Re^3: Regex overlap in MAC address by ikegami
in thread Regex overlap in MAC address by superfrink

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