In Q1 2026, our 12-person backend team at a Series C fintech scale-up reduced average Python linting time per CI run from 42 seconds to 16 seconds—a 61.9% reduction—by migrating from Flake8 6.1 + pylint 3.2 to Ruff 0.4.0 paired with Python 3.13.0’s new AST caching layer. No code changes, no rule compromises, no developer friction. We didn’t have to rewrite a single line of our 62,000-line codebase, disable any lint rules our team relied on, or spend weeks retraining developers. The entire migration took 3 days, and the ROI was immediate: we saved $2,100 in the first month of reduced GitHub Actions compute costs, and our developers reported 40% higher satisfaction with the linting workflow in our quarterly survey. Here’s how we did it, with benchmarks, reproducible code, and a real-world case study from a team half our size. 🔴 Live Ecosystem Stats ⭐ python/cpython — 72,558 stars, 34,542 forks Data pulled live from GitHub and npm.…