There have been many attempts to make a Python JIT that is compatible with CPython to various levels of success. However the larger reason is that the gains from removing the GIL far exceeds the gains from a JIT.
If you're writing performance sensitive python code, the "hot" code is likely already in a C-extension, such as Numpy. So there is negligible benefit to running the code with a JIT.
If you're writing performance sensitive python code, the "hot" code is likely already in a C-extension, such as Numpy. So there is negligible benefit to running the code with a JIT.