Iphone 5 not working properly with iOS 9.2.1

Hello

Since I updated to iOS 9.2.1 my iPhone 5 hasn't worked well or optimally. Examples include: browsing the internet is slow to point where you can't use it, streaming or downloading podcasts slow or not working at all, and intermittent lack of access to emails servers. Should I do a full back up to my computer, then restore the phone to factory settings? Can I then restore the full back up to get all my content back?

Many thanks

Rohan