So I have been playing a lot on my modded survival world recently that includes Alex's Caves, and everything works perfectly normally. But when i entered the toxic caves my frames went from around 65-80 to a peak of 40. Leaving the cave stops all issues, although I brought a Raycat home with me and whenever I looked towards it my frames plummeted once more so it may just be them.
EDIT: did some testing and found out it is specifically the Raycat causing the lag. no clue why.
EDIT 2: so I think the issue is just the radiation glow effect in general. cause me and my friend were playing together and when he got irradiated it lagged just as much as when the Raycat is on screen.

Related to Issue #157

there's an option in the client config to disable the irradiated effect