How the “Shannon Plan” Aims to Double Python’s Speed in 3.11

Guido van Rossum, the creator of Python, announced at the 2021 Python Language Summit that the short‑term goal is to achieve at least a 2× speed increase in Python 3.11. According to the official release schedule, Python 3.10 is in testing and slated for release in October, while Python 3.11 is expected in 2022.

In November 2020, after a year of retirement, Guido returned to join Microsoft’s Developer Division, where Microsoft funded a small Python team that includes core developers, senior software engineer Eric Snow, and research engineer Mark Shannon.

The project, called the “Shannon Plan,” aims to make CPython faster, targeting a five‑fold speedup over four years (about 1.5× per year). A GitHub repository has been created containing a CPython branch, benchmarking tools, and an issue tracker.

Guido emphasized that all work will remain open source and pledged not to break stable ABI compatibility, limited API compatibility, extreme‑case behavior, or code maintainability.

To achieve at least a 2× speedup in Python 3.11, the plan includes a specialized adaptive bytecode interpreter (see PEP 659), stack‑frame optimizations, changes to function call mechanics, more efficient exception handling, startup‑time optimizations, and a revised .pyc bytecode cache format.

The primary beneficiaries will be users running CPU‑intensive pure‑Python code and websites that embed Python. Code already written in C (e.g., NumPy, TensorFlow), I/O‑bound code, multithreaded code, and poorly optimized algorithms will see limited gains.

For more details, see the PDF at https://github.com/faster-cpython/ideas/blob/main/FasterCPythonDark.pdf .