Game frames and studdering

So i dont run a very good pc and i understand that but before the huge patch, my game ran at 60 fps with no studdering. Now, i run 50 fps and it gets worse as the game goes longer and after maybe 10 min its like the frames studder like im blinking repeatedly and its so hard to even continue the game. id rather ff and just get off because its so bad now.

(note: ive done everything in the support page to cleanse my computer of things i dont need, and i set my computer to where i dont run anything i dont need while playing league ie: anything my computer doesnt need to work properly.)

I also play on PBE and the game play is so much purer compared to the NA client for some reason. on PBE i get 65+ frames and the game is clearer and the reaction time to when i click or push a button is 1000 times faster than the NA client(in game)

so im confused if i should just stop playing the game all together until the stuff thats on the PBE currently fps wise comes out for the NA client bc this is so upsetting and im tired of losing games over it.

lmk if i should wait or just give up till i make entire pc changes.

thanks