After I updated my iPad1 (I know it's not the latest apple device, but I'm not an apple fanatic :)) to iOS5, and later to iOS 5.0.1, I noticed that was really slow in the normal usage and applications crashed almost once every hour. At the end I had an iPad but it wasn't a pleasure to use it like the past.
After some tests, I start looking for something to fix these problems, knowing that Apple doesn't allow the downgrade to old versions. And the solution I found, that seems to work after some days of tests, is to reset all settings, going to:
settings -> general -> reset -> restore all (maybe in English the menu names are not exactly these, but my iPad is in Italian :P)
With this reset you don't lose your data (applications, photos, musics, mails, ...) but it just restore the iPad settings to factory default. This means you have to re-enter your wifi key, you have to select your backgrounds but nothing more. An important thing is to prevent restore of these settings from a backup. In fact, after restart, iPad ask you to enter some settings like the first time you start it up: language, location, etc... And then it will ask you if you'd like to restore the device using iCloud or iTunes. Well... Here you have to say NO ;)
Right now, my iPad works like with the previous iOS version: not slow, no apps crashes... At the end I have my iPad back.
Hope this could help someone else.