Understanding uv's Speed Advantage Over pip
Published:Dec 26, 2025 23:43
•2 min read
•Simon Willison
Analysis
This article highlights the reasons behind uv's superior speed compared to pip, going beyond the simple explanation of a Rust rewrite. It emphasizes uv's ability to bypass legacy Python packaging processes, which pip must maintain for backward compatibility. A key factor is uv's efficient dependency resolution, achieved without executing code in `setup.py` for most packages. The use of HTTP range requests for metadata retrieval from wheel files and a compact version representation further contribute to uv's performance. These optimizations, particularly the HTTP range requests, demonstrate that significant speed gains are possible without relying solely on Rust. The article effectively breaks down complex technical details into understandable points.
Key Takeaways
Reference
“HTTP range requests for metadata. Wheel files are zip archives, and zip archives put their file listing at the end. uv tries PEP 658 metadata first, falls back to HTTP range requests for the zip central directory, then full wheel download, then building from source. Each step is slower and riskier. The design makes the fast path cover 99% of cases. None of this requires Rust.”