In the first days after installing iOS 7 on my iPhone 4, I was paying particular attention to the overall performance, trying to verify any iOS 7‑related issue other users and tech websites were reporting. Contrary to other iPhone 4 users’ impressions, with regard to speed, animation and navigation smoothness, so far I haven’t encountered any significant lag or sluggishness that makes me want to go back to iOS 6. 

Something that seems to affect the majority of iOS 7 users, regardless of device, is battery life. Practically everyone I’ve interacted with has complained about the noticeable battery drain under iOS 7. Initially I was puzzled, because on my iPhone 4 I was experiencing the opposite effect and enjoying an extended battery life since updating to iOS 7. I even ventured that iOS 7 may have a better battery management, because in my informal tests it was rather evident that the iPhone 4 was draining less battery power during standby than it did under iOS 6.

Then yesterday I stumbled on this article by the Huffington Post, 9 Ways To Improve iOS 7’s Battery Life, and I started to better understand why iOS 7 doesn’t seem so battery-hungry on the iPhone 4. Let’s review some of the tips, and you’ll notice a pattern emerge:

2. Turn Off AirDrop When Possible

This feature is not present on the iPhone 4.

4. Turn Off Parallax

[…] The aspect of iOS 7 that makes everything look a little bit 3D and makes your background move around behind your apps. It also drains your battery. To turn it off, go to Settings, General, then Accessibility, then Reduce Motion. Turn Reduce Motion on to stop the parallax effect. 

This feature is not present on the iPhone 4.

7. Turn Off Frequent Locations

Your iPhone wants to learn the places you often visit to give you “provide useful location-related information.” This is takes up a lot of battery life and may also make you feel uncomfortable privacy-wise. To disable it go to Settings, Privacy, then Location Services. There, scroll all the way to the bottom and hit System Services. There you can also turn off Location Based iAds (ads from Apple based on your frequent locations). Then go to Frequent Locations and turn that off, too.

This feature is not present on the iPhone 4.

8. Say Goodbye To Siri

Unless you’re using Siri regularly, you’re better off disabling her to save battery. […]

This feature is not present on the iPhone 4.

9. Don’t Use A Moving Background

The new moving backgrounds that iOS 7 offers are super cool, but they will totally kill your battery. To change your iPhone’s wallpaper, just go to Settings, then Wallpapers & Brightness. Try out one of the beautiful new static wallpapers or use a photo of your own.

This feature is not present on the iPhone 4. Only static wallpaper images are available.

As you can see, in this particular instance, having the operating system tailored for a less capable processor, and therefore stripped of certain features (some of them rather unnecessary in the first place) turns out to be a bit advantageous. At least for battery life.

This may explain in part the difference in battery performance between the iPhone 5 family of devices and the iPhone 4. Still, I’m not following other battery-saving tips like tweaking Spotlight settings, turning off Wi-Fi and Bluetooth (most of the time I have Bluetooth off, but I leave Wi-Fi and 3G networking always on), turning down Brightness (it’s always at 65–70%, left unchanged since I bought the iPhone 4 in 2011) or disabling auto-downloads. Even without taking these precautions, since updating to iOS 7 my iPhone 4 on a single charge — and normal usage — lasts about two days, which is roughly 15–18 hours more than under iOS 6. My temporary conclusion is that, while some of the most battery-draining features of iOS 7 are not present by default on the iPhone 4, iOS 7 still displays an improved energy management over iOS 6 — on this device, at least^[1].