If you’ve been trying to use Cydia for the last day, you might have
noticed that it is slow, sluggish, or even unresponsive. Before you
start thinking that your iPhone may be the cause of the problem, relax
and don’t freak out, because it’s not.
Since the release of the iOS 5.0.1 untethered jailbreak yesterday, potentially hundreds of thousands of people have been jailbreaking, launching, and refreshing Cydia sources in the same short period of time, resulting in server overloads for many repos…
Unfortunately, there isn’t much you can do. The only solution is to
wait for things to calm down. I suspect that in a day or two, most
jailbreakers will have already installed the untether, and things will
start going back to normal.
So be patient! In the meantime, you may want to try using Cydia late at night when there is less online activity.