machine:
model name : Intel(R) Core(TM)2 Duo CPU T7250 @ 2.00GHz
stepping : 13
cpu MHz : 2001.000
cache size : 2048 KB
recursive:
real 0m20.581s
user 0m20.473s
sys 0m0.080s
iterative:
real 0m0.005s
user 0m0.004s
sys 0m0.000s
=> 20.581s / 0.005s = 4116.2 times faster