PEP 836 – JIT Go Brrr: The Path to a Supported JIT Compiler for CPython
PEP 836 proposes adding a supported Just-In-Time (JIT) compiler to CPython, the standard Python implementation. It outlines a gradual, multi-phase approach to integrate a JIT to improve performance while maintaining compatibility and maintainability. The goal is to make Python significantly faster by compiling bytecode to machine code at runtime.
Background
PEP 836 proposes adding a formally supported JIT (Just-In-Time) compiler to CPython — the standard, reference implementation of the Python language. Unlike interpreted execution (where each line of bytecode is processed on-the-fly), a JIT compiler translates hot (frequently-run) code paths into native machine code at runtime, often yielding major speed gains. Python has long been slower than compiled languages like C, Rust, or Go, and past JIT efforts (e.g., PyPy, Cinder) were third-party forks, not part of CPython itself. This PEP signals that the Python core team now wants an official, maintained JIT baked into CPython itself — a historic shift in Python's implementation strategy that could improve performance for all Python users, especially in compute-heavy domains like data science, web serving, and AI inference.