CPython 3.13 went further with an experimental copy-and-patch JIT compiler -- a lightweight JIT that stitches together pre-compiled machine code templates instead of generating code from scratch. It's not a full optimizing JIT like V8's TurboFan or a tracing JIT like PyPy's;

Good news. Python 3.15 adapts Pypy tracing approach to JIT and there are real performance gains now:

https://github.com/python/cpython/issues/139109

https://doesjitgobrrr.com/?goals=5,10

> The real story is that Python is designed to be maximally dynamic -- you can monkey-patch methods at runtime, replace builtins, change a class's inheritance chain while instances exist -- and that design makes it fundamentally hard to optimize. ...

> 4 bytes of number, 24 bytes of machinery to support dynamism. a + b means: dereference two heap pointers, look up type slots, dispatch to int.__add__, allocate a new PyObject for the result (unless it hits the small-integer cache), update reference counts.

Would Python be a lot less useful without being maximally dynamic everywhere? Are there domains/frameworks/packages that benefit from this where this is a good trade-off?

I can't think of cases in strong statically typed languages where I've wanted something like monkey patching, and when I see monkey patching elsewhere there's often some reasonable alternative or it only needs to be used very rarely.

Great writeup.

I've been in the pandas (and now polars world) for the past 15 years. Staying in the sandbox gets most folks good enough performance. (That's why Python is the language of data science and ML).

I generally teach my clients to reach for numba first. Potentially lots of bang for little buck.

One overlooked area in the article is running on GPUs. Some numpy and pandas (and polars) code can get a big speedup by using GPUs (same code with import change).

Great post saved it for when I need to optimize my python code

Python is perfect as a "glue" language. "Inner Loops" that have to run efficiently is not where it shines, and I would write them in C or C++ and patch them with Python for access to the huge library base.

This is the "two language problem" ( I would like to hear from people who extensively used Julia by the way, which claims to solve this problem, does it really ?)

A personal opinion: I would much prefer to read the rough, human version of this article than this AI-polished version. I'm interested in the content and the author clearly put thought and effort into it, but I'm constantly thrown out of it by the LLM smell. (I'm also a bit mad that `--` is now on the em dash treadmill and will soon be unusable.)

I'm not just saying this to vent. I honestly wonder if we could eventually move to a norm where people publish two versions of their writing and allow the reader to choose between them. Even when the original is just a set of notes, I would personally choose to make my own way through them.

What a great article!