PyPy is much faster for many workloads. It&#x27;s a garbage collected just-in-time compiler and mostly compatible with the CPython runtime (the one you get from python.org). It also happens to be written in a subset of Python which is pretty neat. The CPython API exposes a bunch of details specific to the CPython implementation (like object reference counts) and so hasn&#x27;t historically been supported in PyPy (which supports the whole language but internally is very different). It sounds like it would be a pain to do but the PyPy team thinks it&#x27;s feasible to build.