Serious FPS decrease in snowy biomes / Lightning artifacts

[RainbowBrejnev]

Minecraft version: 1.12.2, pretty huge modpack (160 mods)

PC:
GTX 1660 Super 6GB
Ryzen 5 2600
32GB RAM
SSD

Mods installed from "opticraft":
CensoredASM 5.20
Alfheim 1.3
Sledgehammer 2.0.26
Universal Tweaks 1.10.0
Fixeroo 2.0

Nothirium 0.3.4 beta
OptiFine U_G6_pre1
Particle Culling 1.4.3

Nether portal fix 5.3.17

Description:
Experiencing huge fps drops in snowy biomes (only), from 250 to 30, when looking into direction of sun or moon (probably? not sure), also experiencing lightning artifacts (screenshots), it's most likely new lightning engine's problem, but who knows, I'll try to disable mods one by one and see the results and write here later;

There are no artifacts/fps drops in other biomes at all. It only appears at night.

Also, here is full config folder of my mods, if you wanna check smth: https://drive.google.com/file/d/1jNp7znniwHAMGzOtk0xdr0FFfYLbtyBd/view?usp=sharing
Optifine config is default.

[Voder830]

Were you able to solve it?

[Voder830]

Do you have Dynamic Surrounding? In my case, it worked by disabling the auroras in the config file