To increase FPS, when using large models, you can use a new mod from the authors: jozufozu and PepperCode1

Vanillin: "Instanced rendering for entities and block entities using Flywheel". Download on Modrinth.

Support the author Vanillin so he can continue to develop this mod and expand it to more versions. This mod is an important optimization that Display entities in the vanilla game are sorely lacking. After installation, go to your game folder and in the /config folder open vanillin.json Opposite the minecraft:block_display and minecraft:item_display values, set force_enable instead of default. Save and start/restart the game.

This is important because support for Display entities is experimental and not enabled by default. Also note that this feature does not work together with shaders and to fix this, you need to install an additional mod: Iris & Oculus Flywheel Compat

Reference image: vanillin_icon.webp.