Using Shaders and a resource pack with CEM at the same time can cause frame drop

Enabling Shader with Iris and loading a resource pack that contains Custom entity models using Entity Model features will cause severe lag. I originally thought it was an issue with EMF, so I discussed it extensively on the EMF Discord. The post is as follows: https://discord.com/channels/950942125225283634/1181977456442355762 Because it would be too long to say everything, let's briefly summarize for now: I found that using Fresh Animation with shader turned on sometimes causes severe lag. I have tried different shaders and resource packs with custom entity models, but the issue persists. I also tested different modpacks like Fabulously Optimized, but it remains the same. In the F3 pie chart, I noticed that render-level-shaders-entities gradually increases during lag and decreases when it recovers. I think it might be an issue with Iris.