Q: iPad running really slow after iOS 8 update

No, you don't seem to understand. First, be clear in your purpose for posting. Do you want to fix your iPad or complain about Apple?  Both are valid things to want to do. I was complaining about the same thing just a few months ago in this very thread. The answer provided solved my issues with my iPad. It does not solve the "issue" with Apple. Just because an update is compatible with your device does not mean it won't gave adverse effects. Many people wait to update until they can get feedback on the update, but you still need to make sure that the review is talking about your same device. Comparing an update on an air2 vs a 4th generation is not the same thing. I unfortunately had to wipe my iPhone 6 plus the other day due to extreme battery issues and set up as new. If I had "restored" from s backup, my issue would still remain. It was less convenient, but in the end, it solved my issue and all I lost were some old texts. Everything else synced back. If you ever want to be mad at software/hardware compatibility issues, go back to a pc. Every time I have to simply use my parents new computer (less than 5 months old) or go over there to "fix" it, I am reminded why I switched to begin with.

Keep in mind also, the money for extra iCloud storage is not so you can update, it is to secure your data for things like a crash or even a stolen iPad. You don't have to do it if you have a computer running iTunes that you back up with frequently. If you don't, .99¢ per mo seems like some good insurance. I was initially mad about that. I have a phone and an iPad. If one device gets 5gb, why shouldn't I get 10?  But it is per user, not device (although I still disagree with the practice). In the end, less than the cost of one can of soda per month seemed worth putting my mind at ease.

I do not mean any of that rude. I completely understand how frustrating it can be. You spend a premium because it is supposed to be better than the others. The same company tells you an update is compatible with your device and then, once installed, it seems as compatible as a squirrel in a cockpit. I do know that the solution given did fix my issue. In fact, I believe my iPad ran better after that with the update than it did prior to the update. Just my two cents. Best of luck.