Benchmark: running list_io, split_slurp, while_io, each for at least 5 CPU seconds...
   list_io:  5 wallclock secs ( 3.89 usr +  1.34 sys =  5.24 CPU) @ 1721.98/s (n=9018)
split_slurp:  4 wallclock secs ( 3.02 usr +  2.21 sys =  5.23 CPU) @ 2725.38/s (n=14251)
  while_io:  7 wallclock secs ( 3.64 usr +  1.38 sys =  5.02 CPU) @ 1629.26/s (n=8174)
              Rate    while_io     list_io split_slurp
while_io    1629/s          --         -5%        -40%
list_io     1722/s          6%          --        -37%
split_slurp 2725/s         67%         58%          --