Terminally slow iPod Touch . . . around midnight?

Question

So, for some time I have noticed that my iPT would intermittently get very, VERY slow. I have only recently noticed that it is fairly consistently doing this around midnight. The problem seems to only last for about five minutes, but it is extremely annoying. While it is in effect, the iPod is virtually unresponsive. Normally, I notice it first by the fact that trying to wake the iPod from sleep mode gets no immediate response. If I put the iPod down for a minute or so (yes, 60+ seconds), the lock screen will appear, but it won't response to me attempting to swipe it. If I'm persistent, I can usually get it to let me in before it's done being slow, and I can watch the transition through the pages of the home screen in response to my swipes simply creep by. The simplest solution to this seems to be to just leave it alone for between 5 and 10 minutes from when I first notice it. Usually, if I do that, it gets back to acting normally.
However, I'd really like to understand what's going on and what to do about it. If it's a hardware issue, I can still send my iPod in to Apple, as it's still under Apple Care.
I already called Apple Care about this, when it first started. The rep I talked to told me that it sounded to him like a software corruption, and if I sent it in they would most likely just send it right back. In an attempt to address this possibility, I have done a restore. When that failed to produce any noticeable improvements, I restored to factory settings, then did not restore from back-up, but instead manually reinstalled everything (losing some data in the process - grrrr). Still seeing the same sort of behavior.
So, as I see it, the options are that there is a hardware issue, or there is an issue with the OS (though I've since updated to the latest 3.1.2), or there is some kind of issue with one of the apps that I've got installed (though, to be honest, if nothing can run in the background except the Apple apps, and this is happening in any state, I'm not sure I see how this could be).
Another possibility that I see is that it could have something to do with the internet connection. I see a similar issue come up occasionally when Mail is checking for new messages and everything seems to get slow for a few seconds (i.e. 5s-10s). Though the magnitude of difference seems inconsistent.
Has anyone else seen this kind of behavior? Does anyone have any ideas what could be causing it? Does anyone have any suggestions about what to do about it?

Answer 1

I agree with Apple, this sounds like a software issue.
Snowy_River wrote:
...or there is some kind of issue with one of the apps that I've got installed (though, to be honest, if nothing can run in the background except the Apple apps, and this is happening in any state, I'm not sure I see how this could be).
That's not true. The AIM app for example runs in the background and pushes IM notifications to you even when you're using a different app. Any app that uses the push notifications can run in the background or there would be no point to the push notification feature.
I would remove all third party applications and try it just to be sure. If the problem goes away with all third party apps removed then do this...
- put back half of the apps and see if the problem comes back.
- If not, put back half of the remaining apps and see if the problem comes back.
- If it does, then focus on that one group of apps and start pulling them off one at a time or by halves until you have the one causing the trouble identified.
Through this process, you should be able to narrow down to the one that's causing it.