This game seems to be super demanding of the CPU, not GPU. I have an RTX 3060 + i5 10400f, running at 1080p lowest settings and render quality at 100%, my avg fps is 90 in lane, but it can drop to around 70 in teamfights. Yesterday I saw someone streaming on Twitch with a RTX 2060 and a Ryzen 7 5800x3d and his game was running at 220+ frames all the time, even in fights.
So yea, very CPU intensive.