JIT (Just-in-time) compiled python
The official implementation of python known as CPython is one of the oldest and still standing implementation of python (as per the statement by Guido Von Rossum himself), being popular among all the implementations, CPython still lacks many much needed features like JIT, multi-threading and generates the byte-code without much compile-time optimizations which makes it much slower to be used in many production environments that process workloads at scale.
(Incomplete)