lagging

i cant even start a match, whenever it finds a match it just stops at the map and waits until i "dodge". riot thinks im dodging but i really cant even get to pick an agent its just showcasing the map for me. and if i do get ingame eventually my fps would be 60 and drop to like 2 in teamfights (seriously, it drops to 2 fps i changed it in settings so i can see how many fps i have) its ridiculous, idk what to do. doesnt happen to any other game for me, not even league of legends