The Shannon Plan: Faster CPython Initiatives for Python 3.13

In autumn 2020, CPython core developer Mark Shannon proposed a series of performance improvements for Python, known as the "Shannon Plan".

He launched the Faster CPython project aiming to make Python five times faster within four years, with Microsoft later joining the effort.

Recent updates from Shannon and Michael Droettboom outline three parallel work streams for Python 3.13:

Tier 2 optimizer : target at least a 50% reduction in interpreter time, with steps to get the Tier 2 interpreter running, generate superblocks, and implement basic superblock management.

Enable sub‑interpreters from Python code (PEP 554) : builds on the per‑interpreter GIL introduced in Python 3.12, allowing better parallelism without writing C extensions.

Memory‑management optimizations : improve data structures to reduce allocations and decrease time spent in cyclic garbage collection.

The plan also mentions an early‑stage JIT effort, noting that a tracing interpreter is the first step and that a full JIT may not arrive until Python 3.13.

Internal debates about removing the Global Interpreter Lock (GIL) are highlighted, with the Faster Python team positioned favorably in the discussion.

Related links: Faster CPython 3.13 proposal and Hacker News discussion .