@sesquipedality @lnr @pseudomonas @mobbsy I’ve found that if it’s doing video processing for HomeKit secure video, a 4 will will run the fan once every minute or so, for a few seconds, to prevent throttling.
So far the 5 seems to run a fair bit cooler. IME, 4S idle at about 60°. The 5 seems to be idling at 50°