How to make a performance test of two versions of Python?

Question

Python

There are two scripts with the same logic, written in different versions of the interpreter.
How to compare their performance not "by eye", but with numbers like in timeit?
Yes, yes, you can run timeit in both interpreters, but where is the confidence that this will be an honest and objective "judging", that is, how to find out that these two timeit are the same?
What are your suggestions, gentlemen?

Answer 1

If you have Linux, it's as easy as shelling pears:
time python2.7 myprog.py
time python3.2 myprog.py

Answer 2

time.time()
variable start assign a value at the beginning of the script to the
variable finish assign a value at the end of the script
subtract from finish start - get the execution time