I've seen various answers to the ball collision detection question explaining why sqrt operations are slow, why absolute value operations are fast on floating ponts etc. How can I find out which operations are expensive and which are not?

Basically, I'm looking for a resource where I can learn about the implementation of all the python library functions. When people are saying those things they aren't actually thinking about how that stuff is implemented in C are they?

Thanks, looking to learn more about implementation details on this slick language.