On average, PyPy is 4.2 times faster than CPython
"If you want your code to run faster, you should probably just use PyPy." -- Guido van Rossum (creator of Python)
Advantages and distinct Features
Memory usage: memory-hungry Python programs (several hundreds of MBs or more) might end up taking less space than they do in CPython.
Stackless: PyPy comes by default with support for stackless mode, providing micro-threads for massive concurrency.
As well as other features.