Benchmark: timing 5000 iterations of Ordinary, Schwartzian...
  Ordinary: 21 wallclock secs ( 6.46 usr + 14.78 sys = 21.24 CPU) @ 235.40/s (n=5000)
Schwartzian: 26 wallclock secs (17.15 usr +  8.45 sys = 25.60 CPU) @ 195.31/s (n=5000)