Benchmark: timing 1000 iterations of join, md5...
      join: 46 wallclock secs (43.51 usr +  0.07 sys = 43.58 CPU) @ 22.95/s (n=1000)
       md5: 55 wallclock secs (53.15 usr +  0.03 sys = 53.18 CPU) @ 18.81/s (n=1000)