I've been building HerdCount — an offline-first iOS app that counts livestock from a photo using YOLOv8n on CoreML. No internet, no account, just the Neural Engine doing its thing.

The app was working, but after adding a share-card feature (a branded "proof of count" image you can send to buyers or vets), I noticed some jank. Tap Save and the UI would stutter. Scroll through results and frames would drop. Nothing catastrophic, but noticeable.

Instead of diving into Instruments myself, I dropped Claude Code into the repo with a performance review prompt and watched what happened.

What it was asked to do

Simple brief: review the codebase for iOS performance issues, particularly in the Result screen and inference path . No specific files called out, no hints. Just "here's the code, find what's slow."

What it found (and actually fixed)

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