In general, you're right - if speed is a concern, loops should be used instead of recursion in Python when possible.
In this case, the recursive overhead is insignificant compared to the expense of iterating over the sequence at every iteration. By the time there are 70 stack frames of recursion (i.e. not much), the sequence is more than 170 million elements long. -- http://mail.python.org/mailman/listinfo/python-list
