Whenever I try to open a chest from the mod my fps drop from 120 constant to 10-15
Minecraft: 1.16.5
Forge: 36.2.34
Iron Chests: 1.16.5-11.2.21

Report Information
There's not much detail to add, just a big fps drop whenever I try to open a chest from this mod, with chests from other mods or vanilla everything works fine. Happens in both solo and server.

I can see this in the console when I tried opening a chest, but I don't understand what it means or how to fix it:

[18:35:13] [main/WARN]: GUI did not draw the dark background layer behind itself, this may result in display issues: net.minecraft.client.gui.screen.inventory.CreativeScreen
[18:35:43] [main/WARN]: GUI did not draw the dark background layer behind itself, this may result in display issues: net.minecraft.client.gui.screen.inventory.ChestScreen
[18:35:51] [main/WARN]: GUI did not draw the dark background layer behind itself, this may result in display issues: com.progwml6.ironchest.client.screen.IronChestScreen

Steps to Reproduce
Open a chest from this mod

Crash Log
No crash log

Forge Log
https://gist.github.com/Distinger/417e4c0fbbf460348b49049b57a6eb02