iCloud Photos process restarting continuously

I noticed in Activity Monitor that the iCloud Photos process is stopping and restarting a few times every minute. The PID is marching up at a pretty regular pace. When a new iCloud Photos process starts up, it uses the CPU for a bit, so I'd like to stop it from running.

Is there any way (a defaults setting?) to prevent this process from running? I don't use iCloud in any way and all of the iCloud services are unchecked in the System Preferences.

I think I've resolved this by installing iPhoto (fortunately I had paid for it before when I wanted to use it before changing my mind), enabling Photo Stream in the iCloud Systems section (without iPhoto I couldn't do this), leave it for a minute then disable Photo Stream. The iCloud Photos process disappeared from Activity Monitor and has stayed away.

It's odd that the preferences could get messed up if you don't want iCloud, but sometimes writing the in-correct settings followed by the correct one clears the bad setting.

Go to iPhoto → Preferences → Photo Stream and disable Automatic Import.