Apple has released the iOS 8.1.1 update, with the specific task of boosting performance on older devices.
The release notes for iOS 8.1.1 simply say this:
iOS 8 launched on September 17, and while it didn't appear to be as big an update as iOS 7's radical design overhaul, it proved to be just as sizeable in different ways.
Here was a mobile OS with a whole host of new features that addressed a number of long-standing criticisms of Apple's mobile OS. It played better with third party apps, contained an improved keyboard, and offered more powerful universal search functionality through Spotlight.
However, from the start, iOS 8 has struggled on older hardware - particularly the iPhone 4S and iPad 2. That's not unusual for one of Apple's new mobile operating systems, which are typically designed with newer hardware first and foremost in mind.
Now, however, Apple is addressing those older devices with iOS 8.1.1. The release also includes a general round of stability improvements and bug fixes.
iOS 8.1.1 is available to download for free now for iPhone 4S, iPad 2 and upwards. To initiate the download, head to Settings>General>Software Update, and ensure you device is either plugged in or is charged to at least 50 percent capacity.