How much does Python optimize?

[Blackbird]

Scott David Daniels wrote:
> Blackbird wrote:
>> I think
>>
>> for i in range(10):
>>     <some code that depends on i>
>>
>> is more readable than a while loop with explicit incrementation of i.
>
>> However, range(10) in the command interpreter obviously returns a
>> list.  Is this list optimized away in the code above, or is it
>> actually constructed internally? (With, say, CPython in one of the
>> recent versions.)
>
> Yup, and if you are tuning a piece of code to the wall, you should
> time it and possibly care.  Likely you are not, and the timing makes
> no difference.  Someday, range will behave like xrange automagically,
> and in the meantime your code will read just fine.  If you are in
> trouble now, your code reads much more like:
>      for i in range(100000):
>          ...

Thanks. Yes, this will be a problem for iterations in the order of 10**5 and
upwards only, and those are rare in most applications.  So my question was
more motivated by a general curiosity about the inner workings of the Python
interpreter, and I sort of understand why advanced optimization on an
instruction set like bytecode would be difficult.  And in the mean time, I
found this insightful piece:

http://www.python.org/doc/essays/list2str.html