Playing on 1.20.1, when searching with JEI and highlighting it, it kills the FPS. Goes from 100 fps down to 10-15fps.

Also not everywhere and not everytime. Sometimes in vanilla storage, sometimes not. Sometimes in modded storage backpacks, sometimes not. It's all over the place when the FPS decide to drop.

Hi @Unrepentant-Atheist, can you let me know in which modpack this happens?

You can try changing the option Max Search Results in the config to a lower value and see if that improves the situation?