Small Python v0.4.0: Close to CPython Speed

Small Python v0.4.0, released on GitHub by developer soasme, now runs at 0.98x–1.1x of CPython speed, up from 1.3x–1.5x slower, after a single Claude Code session with /remote-control enabled was used to benchmark and optimize the project. The author said the agent found and fixed performance opportunities over a day of work, and that after he supplied a few ideas it closed the remaining gap. The release matters as a demonstration of an AI coding agent iterating on a language implementation until it approaches CPython performance.

Small Python v0.4.0: Close to CPython Speed This is a follow-up to the Small Python https://www.julin.ai/2026/10/28/small-python-project/ idea. I burned one more day of tokens to benchmark it and improve the performance. The setup is the same: one single Claude Code session, with /remote-control enabled so that I can prompt it while I’m out. In the morning I attended a local farm event, and in the afternoon we went trick-or-treating for Halloween. The agent is capable of finding opportunities and fixing them correctly. Often it can run a few hours before it prompts me with more potential things to fix. I generally just ask it to continue. At one point it stopped and claimed it wouldn’t gain much more, while it was still 1.3x–1.5x slower than CPython. I gave it a few ideas, and now it runs at 0.98x–1.1x of CPython. In the end, I’m more than happy to ship a new version: Small Python v0.4.0 https://github.com/soasme/small-python .