If you have an older iPhone or iPad with a small amount of memory, you may experience sluggishness when you have several Apps open. One thing you can do to alleviate this situation is clear the device memory (RAM). Here are two ways to do this.
Clear Device Memory
The simplest way to clear the memory on your iDevice is to simply Restart it.
This takes a minute or two out of your workflow. There is another way to do this and that is to download and install a free App called CPU-x from the App Store.
Once you are in this App, you will see all kinds of information on your device which is helpful. Tap on the Memory setting to get to the memory clear window.
Once in the memory clear window, you can see your “Available Memory” in the list.
Tap on “Free up” and CPU-x makes more memory available on your iPhone.
You can watch the “Free” memory increase while it optimizes. When it is finished, it will tell you how much memory it has recouped.
You can do this several times. The App will free up memory each time, albeit a little less memory than the first attempt.
I am using CPU-x in iOS 14, but it is supposed to work on iOS 13 as well. There is a paid Pro version for $1.99 which I did not buy. The Pro version adds a couple of features and removes any ads.
It is not a bad idea to Restart your iPhone from time to time. If you are using many Apps and feel things slowing down on your iPhone, you can just use CPU-x to clean things up a bit.