Battery life is pathetic after installing iOS 5

Question

The battery life for my iPod Touch 3rd gen. has been incredibly bad ever since I installed iOS 5, when it was first released a few months ago. The 5.0.1 update didn't help, either. I used to be able to comfortably charge my iPod "just" once a day, but now it's often more than two full charges that are required per day. My usage patterns, of course, have not changed over the past few months compared to when I first got the iPod Touch.
Is there anything I can do to improve battery life, or check its capacity, since I've had it for a while and perhaps its capacity has gone down?
Also, the device's performance has gotten much slower since installing iOS 5, too. I heard that the Notification Center is a primary cause for those problems, so I disabled most things in it, except for Mail and Weather since those are important to me.

Answer 1

I haven't done any scientific testing, but I'd say that I can get maybe two to four hours if I'm just browsing the web, when it used to be perhaps upwards of six to eight hours a day. I do indeed do some gaming, but most of my time is spent on todo items and web browsing. I have definitely not changed how I use the device since I first bought it, which was about two or three years ago, so if there is a noticeable difference then I will perceive it. Also, nearly every day I use the device from a full charge (charged overnight) to automatic shutoff (0% battery), because it hits the "red zone" for the battery quite quickly (about an hour of usage) then the remaining time is spent in the red zone.
For some reason, the battery also leaks quite significantly when I'm not even using it, which from what I understand is also a fairly common occurrence with iOS 5, as well. I think that this is actually where most of the battery life goes to, rather than from me actually using the device.