iPod touch slow with problems
So I got my iPod touch (fifth-generation, 64GB) back in 2013. I dropped it in water, so I traded it in at an Apple Store for a new iPod touch. Ever since updating the iPod to iOS 8, it's been having multiple problems, including: General unresponsiveness for up to 30 seconds; crashing, failing to properly execute basic animations, and lagging when doing pretty much anything; dropped frame rate during animations; random freezing, sometimes up to 10 minutes of it, even when locked, until iPod reboots; excessively long reboot out of previously mentioned freezing, sometimes up to 15 minutes; etc.
Usually when I pick it up, it says that I have to enter the passcode because iPod restarted, and it'll be disconnected from all Wifi. This is a problem, especially if it gets stolen.
Any recommendations for what I can do to stop this? Is this behavior normal for fifth-generation iPod touches? Or am I stuck with it?
iPod touch, Windows 7, iTunes 11