The traps are not always well known (to me).<p>For example, I just discovered a few days ago while porting a Python2 library that byte concatenation is an O(N^2) procedure in Python3 while it is an O(N) procedure in Python2.<p>So you have to use bytearrays and really rewrite all the code that deals with bytes. Basically, even if something works, you still have to performance profile.