git fsmonitor
Built-in filesystem monitor (git 2.37+, 2022) — speeds up git status on huge repos by listening for FS changes instead of scanning the entire worktree.
git config core.fsmonitor true. Inspired by Microsoft's setup for the Windows monorepo. Earlier alternative: Watchman from Facebook. Difference: usually 10-100× speedup on repos with 100k+ files (Chromium, Linux kernel, NixOS).