Time Machine crawling for 12+ hours (~180 million changed files) after heavy AI/dev work, 53.1% to 53.3% in 5 hours

Mac model: MacBook Pro (Mac16,8), Apple M4 Pro, 24 GB

macOS version: macOS 27.0.1 (26A434)

Backup destination: WD_BLACK external drive, connected locally

I use this MacBook heavily for AI-assisted development (Cursor and similar tools): many git repos, node_modules, Python virtualenvs, build caches and local model files.

Time Machine found roughly 180 million changed files and has been backing up for about 12 hours. In the last 5 hours progress moved only from 53.1% to 53.3%, with 172.3 GB copied. The Mac is on power and awake. Backups used to finish in reasonable time before this volume of small, high-churn files.

1. Are others seeing Time Machine effectively stall because of node_modules, .git churn, caches and AI tooling folders?

2. Is excluding regenerable folders (Settings or tmutil addexclusion -p) Apple's recommended approach for developers?

3. Is there any supported way to exclude by folder name? Patterns like */node_modules don't seem to work.

4. Should I skip this backup, add exclusions and start fresh, or let it run?

Happy to share tmutil status output.

Posted on Nov 2, 2026 3:24 AM

1 reply

etresoft

Level 9 (60,836 points)

Nov 2, 2026 4:52 AM in response to koosvderstrauss

koosvderstrauss wrote:

Are others seeing Time Machine effectively stall because of node_modules, .git churn, caches and AI tooling folders?

Nope. Wouldn't touch that stuff. Time Machine doesn't support it anyway. The last time I used Time Machine git complained about the checksums on files I had restored.

Is excluding regenerable folders (Settings or tmutil addexclusion -p) Apple's recommended approach for developers?

Yes.

Is there any supported way to exclude by folder name? Patterns like */node_modules don't seem to work.

You already know about tmutil add exclusion. Why would you care about a pattern like this? Time Machine is designed for user documents. There are many problems if you try to use it with typical developer files.

Should I skip this backup, add exclusions and start fresh, or let it run?

Definitely skip it and reconfigure.