# Python 3.15 adds lazy imports and built-in sampling profiler

_Published Monday, October 12, 2026 at 2:51 PM EDT · Infrastructure · Latest · Tier 2 — Notable_

![Python 3.15 adds lazy imports and built-in sampling profiler — Primary](https://static.simonwillison.net/static/2026/profiler-output.webp)

Python 3.15 is available with explicit lazy imports and a sampling profiler in its standard library, developer Simon Willison writes. Lazy imports defer loading a module until its symbols are first used, addressing startup delays from heavy dependencies. The profiler periodically captures stack traces from running processes to identify where execution time goes without first instrumenting the program.

The release also ends official support for Python 3.10. Willison says that lets his projects adopt Python 3.11 features while continuing to support every maintained version. Performance tests he cites found Python 3.15 mostly unchanged from 3.14; an experimental just-in-time compiler delivered a 1.2x improvement on a Fibonacci test.

## Sources

- [Simon Willison's Weblog](https://simonwillison.net/2026/Oct/12/python-3-15/)

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Canonical: https://techandbusiness.org/newswire/wiRKUsYOy7VuzEdbL-BNbA
Published: 2026-10-12T18:51:15.809Z
Story chronology: 2026-10-12T18:15:38.000Z
Retrieved: 2026-10-12T21:48:09.023Z
Publisher: Tech & Business (techandbusiness.org)