Why is early return slower than else?

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This is a follow-up question to an answer I gave a few days back. Edit: it seems that the OP of that question already used the code I posted to him to ask the same question, but I was unaware of it. Apologies. The answers provided are different though!

Substantially I observed that:

>>> def without_else(param=False):
...     if param:
...         return 1
...     return 0
>>> def with_else(param=False):
...     if param:
...         return 1
...     else:
...         return 0
>>> from timeit import Timer as T
>>> T(lambda : without_else()).repeat()
[0.3011460304260254, 0.2866089344024658, 0.2871549129486084]
>>> T(lambda : with_else()).repeat()
[0.27536892890930176, 0.2693932056427002, 0.27011704444885254]
>>> T(lambda : without_else(True)).repeat()
[0.3383951187133789, 0.32756996154785156, 0.3279120922088623]
>>> T(lambda : with_else(True)).repeat()
[0.3305950164794922, 0.32186388969421387, 0.3209099769592285]

…or in other words: having the else clause is faster regardless of the if condition being triggered or not.

I assume it has to do with different bytecode generated by the two, but is anybody able to confirm/explain in detail?

EDIT: Seems not everybody is able to reproduce my timings, so I thought it might be useful to give some info on my system. I’m running Ubuntu 11.10 64 bit with the default python installed. python generates the following version information:

Python 2.7.2+ (default, Oct  4 2011, 20:06:09) 
[GCC 4.6.1] on linux2

Here are the results of the disassembly in Python 2.7:

>>> dis.dis(without_else)
  2           0 LOAD_FAST                0 (param)
              3 POP_JUMP_IF_FALSE       10

  3           6 LOAD_CONST               1 (1)
              9 RETURN_VALUE        

  4     >>   10 LOAD_CONST               2 (0)
             13 RETURN_VALUE        
>>> dis.dis(with_else)
  2           0 LOAD_FAST                0 (param)
              3 POP_JUMP_IF_FALSE       10

  3           6 LOAD_CONST               1 (1)
              9 RETURN_VALUE        

  5     >>   10 LOAD_CONST               2 (0)
             13 RETURN_VALUE        
             14 LOAD_CONST               0 (None)
             17 RETURN_VALUE

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