I have reported this issue also with The One Probe: McJtyMods/TheOneProbe#552 (comment)

Minecraft Version: 1.18.2
Forge Version: 40.0.54
The One Probe Version: theoneprobe-1.18-5.1.0.jar
Taterzen: taterzens-1.8.6-forge.jar

Create a NPC
Look at it and experience FPS drop ( mine went from a steady 60 FPS to 15-20 FPS

The latest.log file was to large for pastebin, so i added the file here. Basicly it is the same error over and over again.
This is a log file while 1 min in game (more or less)
latest.log

Please report this on theoneprobe issue tracker.

This still happens on the latest Forge release.

error: https://gist.github.com/MattB70/9175732c4cecf74ec61cb24aef0aa6ab