Which is faster in Python: x**.5 or math.sqrt(x)?

I've been wondering this for some time. As the title say, which is faster, the actual function or simply raising to the half power? UPDATE This is not a matter of premature optimization. This is simply a question of how the underlying code actually works. What is the theory of how Python code works? I sent Guido van Rossum an email cause I really wanted to know the differences in these methods. My

[bellbind]

math.sqrt(x)より、x ** .5 のほうが早いという件