Two questions regarding App Store Purchase history and iOS 8.1.1

Nov 14, 2008
Cairo, Egypt.
Hello there guys

I am using an iPad 3 running 8.1 and the performance is totally horrendous in terms of speed and response times. Updating to iOS 8 was probably the biggest mistake I have done since I got this iPad and of course I cannot downgrade to iOS 7 since it is no longer being signed, however does the latest 8.1.1 improve the speed or is it all the same minus some useless bugs?

And my second question is: I play an online game called Boom Beach where the profile (backup, in other words) is linked to my Game Center account. Now I want to create a different account as I no longer use the other one, so I logged out of my original Game Center account, created a new Apple ID, signed in, and redownloaded the game but on the App Store it no longer says "Install" but rather gives me this cloud icon in order to install the game, and when I do so, it restores the game with all the data that was on it which I don't want.

So in short, how do I perform a fresh installation of the game without having it automatically restore the data that was on it and the profile?

Thank you.