Same here, with an idling Django app. Auto-reload is on (vanilla runserver command), but no files are changing and I’m not viewing the site. com.docker.hyperkit bounces between 70% and 135%, and com.docker.osxfs from 25-40%. Stopping that container (and leaving my other docker-compose containers running) makes them both drop to under 1%.
Edit: I followed the advice here High CPU usage for Django application and installed pyinotify. Fixed it!