Okay.
If you install fargo and calamity mods along with theur compatibility mods, terraria overhaul and glaze it with fancy lightning on top. When you fight against certain bosses, there's horrible fps drops up to 2-5 fps from 60 stable.

(U need to enable combined difficulty of fargo-calamity. idk, it's something about ai logic problem that is amplified with lightning bugs of these mods combined with fancy lightning.).

I noticed it with mecha destroyer and all of exo mech bosses.

I write it because maybe you'll check how your mod conflict with these mods? Because as i can see, fargo, overhaul and calamity simply do not have a ♥♥♥♥ about their mods performance or bugs itself.