The bundle setting

Tuning monorepos involves a dozen settings. Rather than memorize and apply each, Git provides "feature flags" that activate a coherent bundle. feature.manyFiles is the most useful: one knob that enables all the index and stat optimizations.

What it sets

• index.version=4 — prefix compression.
• core.untrackedCache=true — cache untracked listings.
• (Implicit) recommended index reading paths.

git config feature.manyFiles true
git config --list | grep -E '^(index|core)\.'

Sister features

• feature.experimental=true — turns on cutting-edge perf flags being evaluated for default-on.
• Historical: feature.manyCommits appears in some Git versions; behavior may vary by build.

See "Feature.experimental and feature.manyCommits".

Combining with monorepo stack

git config feature.manyFiles true
git config core.fsmonitor true
git config core.commitGraph true
git sparse-checkout init --cone --sparse-index
git maintenance start

This is the canonical setup for repos with hundreds of thousands of files.

Behavior across versions

The exact set of settings feature.manyFiles activates may change across Git versions. Treat it as opinionated defaults that the Git project tunes for you. Inspect with git config --show-origin --list after enabling.

Verifying impact

time git -c feature.manyFiles=false status
time git -c feature.manyFiles=true status
GIT_TRACE2_PERF=1 git status 2>&1 | head -50

Common mistakes

Setting feature.manyFiles=true without running git update-index --index-version=4 on an existing repo — the policy is set but the on-disk index stays old. Re-running git status rewrites it, but you can force it:

git update-index --index-version 4
git status                                # rewrites with new defaults

Reset

git config --unset feature.manyFiles
git update-index --index-version 2

Related

See "Configuring index.version for performance", "Feature.experimental and feature.manyCommits", and "Fsmonitor: faster working tree queries".