Once again, FPS drops while playing Sivir against Dark Star Thresh

I've already made a post about this weeks ago, so it's extremely infuriating that it still exists. Once again, while playing as Sivir, everytime the enemy team's Dark Star Thresh was on screen, my fps would drop from 70+ to around 10. Except unlike last time I posted this, this time it happened with them on the enemy team. So I've now seen it happen both while on my team and on the enemy team. It'd be very nice if someone from Riot could respond and tell me if this is something on my side that I can fix, or if it's something else entirely that they actually know about and are working on. Being 10 FPS against a Thresh in a ranked game is really not fair at all.