Select Code to Download

use Modern::Perl;

...
    my @big   = split ':', $_[1];
    @small ~~ [ grep $_ ~~ @big, @small ];
}

sub isSubset {
    my $count = my @small = split ':', $_[0];
...
    do { $count-- when @big } for @small;
    !$count;
}

use Modern::Perl;
use Benchmark qw(cmpthese);
...
        isSubsetHash    => sub { say isSubsetHash( $b, $a ) },
    }
);

                    Rate      isSubset    isSubsetHash isSubsetSmarter
isSubset        143452/s            --            -15%            -54%
isSubsetHash    169263/s           18%              --            -45%
isSubsetSmarter 309705/s          116%             83%              --