sub faster {
    return 0 unless $_[0];
    @_ = ($_[0] - 1);
    &faster;
}

##</code><code>##

cmpthese( -10, {
        "normal" => sub { normal(50000) },
        "tail"   => sub {   tail(50000) },
        "faster" => sub { faster(50000) },
    }
);

##</code><code>##

         Rate normal   tail faster
normal 2.34/s     --    -0%   -41%
tail   2.35/s     0%     --   -41%
faster 3.96/s    69%    68%     --