ios 11.2.1 fps drops, choppy animation [ipad mini 4]

Hello, Apple Community.

I'm writing these post specially for Apple Programmers who are developing ios (I hope they will read it).

I made dfu restore to ios 11.2.1 (couple of days ago I used ios 10.3.3), made clean installation (no backup restore). And what I found on my shiny new ipad mini 4 using last AMAZING operation system? FPS drops in App Switcher (just try to switch app cards [more than 6 opened apps] or choose app card and click on it), Control Center (when you're opening stock with wi-fi, AirDrop, Airplane mode, Bluetooth, or other controls in CC [animation of opening/closing is NOT smooth. Try it on different device - iPhone 6s for example - it doesn't have this problem on ios 11.2.1] ). FPS is dropping even if you are trying to open Notification Centre with notifications from UP side.

I noticed here only VERY ANNOYING system bugs/lags - system choppy animation.

Apple, you didn't get me downgrade option. I stuck with ios 11.2.1. I'm not satisfied with user experience and I even don't know where I can post it to tell these problems to ios programmers.

MAKE IOS GRATE AGAIN