Benchmark: timing 10 iterations of with, without...
      with: 17 wallclock secs (13.56 usr +  0.24 sys = 13.80 CPU) @  0.72/s (n=10)
   without: 17 wallclock secs (15.34 usr +  0.02 sys = 15.36 CPU) @  0.65/s (n=10)