I can't play lol ;-;

Hello everyone. i wrote this because for like 1 week i can't play lol anymore , Why ? because when i start Lol idk why but it lag soo MUCH also when i try to connect my frame on the login screen are so low and when i try to connect it lag again but the connection succefully done but it lag. i didn't try to play but i won't try because i think that it will be worst. So , after that i rebooted my pc but it didn't change anything. I started another game (overwatch) and there is no probleme ( +110 fps ). i reinstalled lol two times but it didn't work also ...

I don't understand why because i have a really good computer it's really weird , isn't it ?

if anyone have an answer or somthing that can fix this probleme , can he share it to me ?

bye ! (sry my english is not very good :)