Rate _substr _unpack  _regex  _split
_substr 2187335/s      --    -11%    -16%    -20%
_unpack 2457294/s     12%      --     -6%    -10%
_regex  2612321/s     19%      6%      --     -4%
_split  2726283/s     25%     11%      4%      --