Rate array_diff array_same  hash_diff  hash_same
    array_diff  916/s         --       -10%       -16%       -25%
    array_same 1012/s        11%         --        -7%       -18%
    hash_diff  1092/s        19%         8%         --       -11%
    hash_same  1229/s        34%        21%        13%         --