I've been wondering lately how various operations I perform on basic types like strings and integers work in terms of performance, and I figure I could get a much better idea of this if I knew how those basic types were implemented (i.e. I've heard strings and integers are immutable in Python. Does that mean any operation that modifies one character in a string is O(n) because a completely new string has to be created? How about adding numbers?)
I'm curious about this in both Python and Perl, and felt silly asking basically the same question twice, so I'm just wrapping it into one.
If you can include some example operation costs with your answer, that would make it even more helpful.