Speeding up a Git monorepo at Dropbox with <200 lines of code

This post details how Dropbox addressed Git performance degradation in its large monorepo, particularly on macOS. The solution involved a combination of upstream Git improvements (fsmonitor, untracked cache, split-index mode) and a small wrapper script (<200 lines of code) to automatically configure Git for developers. This resulted in significant reductions in p50 and p90 durations for common Git operations like `git status`, without fragmenting the repository or requiring additional services.