Python 3.0 was slower than Python 2.7, largely because some new modules were initially implemented in pure Python in order to get the APIs out there for people

Python 3.0 was slower than Python 2.7, largely because some new modules were initially implemented in pure Python in order to get the APIs out there for people to experiment with. They're since been replaced with implementations in C. Python 3 passed Python 2 on performance years ago.