A question about osyco

[iu2]

Hi guys,

I wrote two version of a fib functions, a recursive one and an
iterative one.
Psyco improved a lot the recursive function time, but didn't affect at
all the iterative function.

Why?

Here is the code:

import time, psyco

def mytime(code):
    t = time.time()
    res = eval(code)
    delta = time.time() - t
    print 'Code:', code
    print 'Result:', str(res) if len(str(res)) < 20 else str(res)[:10]
+ '...'
    print 'Time:', delta
    print

def fib1(n):
    if n <= 1: return 1
    return fib1(n-2) + fib1(n-1)

def fib2(n):
    x, y = 1, 1
    for i in xrange(n-1):
        x, y = y, x + y
    return y

mytime('fib1(32)')
print 'psyco'
psyco.bind(fib1)
mytime('fib1(32)')

mytime('fib2(100000)')
print 'psyco'
psyco.bind(fib2)
mytime('fib2(100000)')


And the output:
----------------------

Code: fib1(32)
Result: 3524578
Time: 2.74499988556

psyco
Code: fib1(32)
Result: 3524578
Time: 0.119999885559

Code: fib2(100000)
Result: 4202692702...
Time: 5.53900003433

psyco
Code: fib2(100000)
Result: 4202692702...
Time: 5.46900010109