'xx556xx' ---> qw(xx 55 6 xx)

my @Array = keys %{{$String =~ m/((.)\2*)/g}}

my %count;
my $max;
for (split //, $string) {
  $max = $count{$_} if ++$count{$_} > $max;
}

my @x = "xx556xx" =~ m/((.)\2*)/g;
@x = map { $x[2*$_] } (0..@x/2-1);

use strict;
use warnings;
use Benchmark qw(:all);

my $s = 'xx55111111116jkwhcxxxxx';

sub test1 {
    my $r;
    my $r0;
    my @R;
    for my $c (split '', $s) {
        unless (defined $r) {
            $r = $c;
            $r0 = $c;
        } elsif($c eq $r0) {
            $r .= $c;
        } else {
            push @R, $r;
            $r = $c;
            $r0 = $c;
        }
    }
    push @R, $r if length $r;
    @R;
}

sub test2 {
    keys %{{$s =~ /((.)\2*)/g}}
}

sub test3 {
    my @x = $s =~ m/((.)\2*)/g;
    map $x[2*$_], 0..@x/2-1;
}

cmpthese (-20,
    {
        for => \&test1,
        pKai => \&test2,
        murphy => \&test3,
    }
);

         Rate    for murphy   pKai
for    5172/s     --   -12%   -27%
murphy 5866/s    13%     --   -18%
pKai   7123/s    38%    21%     --

my @sequences = $string =~ m/((??{'(.)\1*'}))/g;

my $re = qr/(.)\1*/;
my @sequences = $string =~ m/((??{$re}))/g;