iPhone 4S and iPad 2 is faster with new update
Apple working on iOS update that provides more speed on older devices.
One of the improvements in addition to general safety and stability is that it improves speed if you have older devices like the iPhone 4S and iPad 2nd.
Apple has received some criticism from users of older devices almost every time they update iOS. Most of the complaints are about the decrease in speed. This applies both for the update to iOS 8 as was the case especially with iOS 7 where many saw that speed was significantly worse.
However, you have some other methods to do in order to ensure that older equipment running optimally by resetting the network settings in System Preferences.