Minecraft - Heavy FPS drop in certain area of the map

I play with a friend and we have some mods installed on our server. However, my friend has MASSIVE FPS burglaries of up to 2 or 3 FPS in a specific area of about 1-3 Chunk.

He estimates it's related to Cooking for Blockheads or Harvestcraft. He says the big kitchen would make it all so hard to calculate (lots of stuff in the fridge from which things are taken while crafting)

Could you give an idea if it really is and / or what you could do (except remodeling the kitchen)?

Best regards!

P.S.: In the appendix a listing of the mods. Play on 1.12.2

4 GB additional RAM on the server

Probably many of the modified items in the part of the map are many entyties (items that are on the ground, animals, players, mobs, etc.) or much that needs to be rendered.

That brings your Minecraft to Laggen. Is it the same with your friend?

With me it is not a problem, but with him. His calculator is weaker than mine. So far, he had no problems, but now probably make the many Entyties in the refrigerator (Yes, in 3D, if you open the door) problems. Is that possible? What else can you do?

I'm not familiar with this mod, but otherwise he can only assign Minecraft more RAM. There are many tutorials on YT, but not more than half. I've tried what happens when you use all the RAM, it does not change that much, except that when you raustabbt one of the computers, it looks like one from 1980.