or download this
Benchmark: timing 200 iterations of lookahead1, lookahead3, lookahead4
+, lookahead5, nolookahead...
lookahead1: 3 wallclock secs ( 2.93 usr + 0.00 sys = 2.93 CPU) @ 68
+.26/s (n=200)
lookahead3: 2 wallclock secs ( 2.23 usr + 0.00 sys = 2.23 CPU) @ 89
+.69/s (n=200)
lookahead4: 2 wallclock secs ( 2.03 usr + 0.00 sys = 2.03 CPU) @ 98
+.52/s (n=200)
lookahead5: 2 wallclock secs ( 2.00 usr + 0.00 sys = 2.00 CPU) @ 10
+0.00/s (n=200)
nolookahead: 7 wallclock secs ( 6.30 usr + 0.00 sys = 6.30 CPU) @ 3
+1.75/s (n=200)