HUGE FPS DROPS either morde or garen is the culprit
So I just played a game with 2 mordes and 2 garens.
Either Morde's armor or Garen's spin was causing severe fps drops. (Not my team's garen or morde tho) so it has to be the skin difference.
Morde was using the Infernal skin and Garen was using the Steel Legion skin.
It wouldn't be all the time, only sometimes. I think I got it down to the morde W or the Garen spin. (It happened in team fights or when I'd watch the enemy while dead/far away)