GoKawiilPython 3.15 alpha adds lazy imports via PEP 810, new flake8-lazy tool helps libraries adopt it
Python 3.15a7 now supports lazy imports, a feature described in PEP 810 that delays loading modules until they are actually used, speeding up things like CLI startup and --help commands. Unlike a previous failed attempt at automatic lazy imports, this version requires library authors to explicitly opt in, so the author built a helper tool called flake8-lazy to automate the necessary code changes.
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Many Python programs and libraries import far more code than they actually use at runtime, which slows down startup, especially under newer tools like uv that skip bytecode precompilation for faster installs. By requiring explicit developer action rather than automatic behavior, PEP 810 avoids the pitfalls of earlier attempts while still offering meaningful performance gains once libraries adopt it.
- Python 3.15a7 introduces lazy imports as defined in PEP 810, improving performance for CLI tools and import-heavy codebases.
- Adoption requires developers to modify their code, unlike a previous failed automatic approach, so a new tool called flake8-lazy was created to simplify the process.
- The tool's development also served as the author's first deep experiment using AI assistance for library engineering, a topic explored later in the writeup.
Fluent Python" by Luciano Ramalho (2nd Edition) — If posts about lazy imports and PEP internals get you curious, this is the book that explains why Python behaves the way it does under the hood. Ramalho digs into the data model, imports, modules and idiomatic patterns so you can write code that's fast and genuinely Pythonic. A great desk companion while you're refactoring your imports for 3.15.
See Fluent Python" by Luciano Ramalho (2nd Edition) on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: iscinumpy.dev — Henry Schreiner, 2026-09-01
Published there as: “Working to Make Python Lazy”
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