[dagw]

Has a CPython JIT been ruled out for some reason

There have been several attempts at integrating a JIT into CPython. Google made a stab at it back around version 2.6 and there was a second attempt around the 2->3 change to build a JIT on top of LLVM. However none of these projects produced results that the core developers felt were good enough across the board and had problems with backwards compatibility and lot cross platform LLVM issues (as it was a pretty new project) so they were dropped after Google stopped funding the project.

That being said there is still work being done and people are hoping for at least some JITing in upcoming python. Pyston is project being worked on Guido Van Possum himself and both Microsoft Instagram have their own JITed versions of Python they use internally. Some initial parts of Pyston are even scheduled for being included in python 3.12 or 3.13