I benchmarked my own desktop pet and found it running OCR ten times a minute

A pet is idle 99% of the time, so idle is the only number that matters. While measuring battery I found my own behaviour loop calling screen capture and OCR on every tick, forever, with no way to turn it off.

The fix was not a time cache - that returns stale frames when the screen does change. It was a positive signal that nothing changed: no input and no active app switch since the last capture, plus a thumbnail comparison.

The part I still cannot do honestly is quote a watts-per-process number: measuring that on Apple Silicon needs sudo, and powermetrics gives an estimate. If anyone has a method they trust for a background app, I would like to hear it.