Short string:
               Rate   triple-s join-split   double-s
triple-s   305867/s         --       -31%       -37%
join-split 441107/s        44%         --        -9%
double-s   482473/s        58%         9%         --

Long string:
              Rate   triple-s join-split   double-s
triple-s    4775/s         --       -69%       -86%
join-split 15251/s       219%         --       -55%
double-s   33822/s       608%       122%         --