Benchmark: running forloop, forloop2, merge, slice, whileloop, whileloop2, each for at least 2 CPU seconds...
   forloop:  3 wallclock secs ( 2.22 usr +  0.00 sys =  2.22 CPU) @ 108.11/s (n=240)
  forloop2:  2 wallclock secs ( 2.09 usr +  0.01 sys =  2.10 CPU) @ 122.38/s (n=257)
     merge:  2 wallclock secs ( 2.10 usr +  0.00 sys =  2.10 CPU) @ 176.19/s (n=370)
     slice:  2 wallclock secs ( 2.14 usr +  0.00 sys =  2.14 CPU) @ 140.19/s (n=300)
 whileloop:  2 wallclock secs ( 2.16 usr +  0.00 sys =  2.16 CPU) @ 87.04/s (n=188)
whileloop2:  2 wallclock secs ( 2.07 usr +  0.01 sys =  2.08 CPU) @ 110.10/s (n=229)
             Rate whileloop   forloop whileloop2  forloop2      slice      merge
whileloop  87.0/s        --      -19%       -21%      -29%       -38%       -51%
forloop     108/s       24%        --        -2%      -12%       -23%       -39%
whileloop2  110/s       26%        2%         --      -10%       -21%       -38%
forloop2    122/s       41%       13%        11%        --       -13%       -31%
slice       140/s       61%       30%        27%       15%         --       -20%
merge       176/s      102%       63%        60%       44%        26%         --