# my $input = join ' ', (1) x 1_001, ('+') x 1_000;
            Rate recursive iterative
recursive 83.6/s        --      -80%
iterative  415/s      396%        --

# my $input = join ' ', 1, ('1 +') x 1_000;
            Rate recursive iterative
recursive 82.2/s        --      -78%
iterative  376/s      357%        --

# my $input = join ' ', (1) x 4, ('+') x 3;
             Rate recursive iterative
recursive 28249/s        --      -69%
iterative 92593/s      228%        --