Client minimizes itself and dropping framerates in-game

Hey y'all!

I am just a casual and normal LoL Player with an under average pc. i call it lovingly "pile of trash". But still there are some things i cannot oversee, so i looked into them deeper.

The first thing is that for 3 Days only during SR Ranked Games my in-game Window minimizes itself with nothing else running in the back or something. I already checked a ticket that was 3 Years ago, stating that some Windows 10 Update or a Windows Office bug was creating a window which forces itself in the front was behind that problem. But i neither use Windows office nor do i have that Windows Update from 3 Years ago. But still there is something interrupting me (at times escaping or even during a fight) in my game.

Second thing is something i already checked 2 Months ago due to me having in-game framedrops that massively worsen my Gameplay. I started having some framedrops from (normally) 50 to 10 or even a freezed image for about 1 or 2 seconds. Lowering my Graphics from normal to the lowest didn't help, instead it even made it worse. I am playing now at 40 FPS and that still drops to 5 or even 1 or 2 when nothing is happening. there is a 5 second cycle from dropping to 5 and then back up to 40 just to go back down to 5. After loosing many fights and games due to this problem i started re-installing League but still no fluid game. I did the whole thing, but nothing helped. Then i started searching the forums for a help or at least other people with the same problem (because a friend of mine said it was due to Riot) and i found some. Other People with some Pretty high gear still said they had framedrops of 75% (from 200 to 50 e.g.) since the release of TFT (or Set 2 at least) and Riot Support only told them to "gear up". So here i am writing this half-angry paragraph about 2 Problems that i now have but can't be from my Hardware so i am asking this to the riot support.

Thanks a lot for reading this and have a nice day :) Yours Syntax631