Just started playing yesterday, I’ll update this as I find them. I cap at 60fps. Whether I play on Very High or Very Low it’s exactly the same, no setting seems to affect these spells. They definitely need to be re-made/removed since I don’t have any issues elsewhere.
Drowned Visage: When he uses his spell that explodes into an aoe, FPS drops to around 35.
Primeval Dragon: When he uses his fireballs it drops to 30 FPS.
Imperial Welryn: Drops to about 40 FPS after it channels explosion.