[BUG] Large Framerate Drop When Looking at Entities with FreshAnimations Resource Pack and Complimentary Shaders 5.0.1 When PBR Enabled

[jetblackrx89]

Describe the issue

• Frame rate drops from about 50-60 fps to 5-10 fps when facing a 10x10 fence with 20 cow entities.
• Loaded ETF with default settings, the FreshAnimations resource pack, and Iris and ComplementaryReimagined r5.0.1 shaders, which I believe was a major re-write of that shader pack. Issue isn't seen with ComplementaryReimagined r2.3. Issue isn't seen if PBR is turned off entirely in the shader options. Issue isn't seen if FreshAnimations resource pack is disabled.

Your setup: (please complete the following information):

• Minecraft version: 1.20.2
• ModLoader: Quilt-Loader-0.21.0-1.20.2
• ETF Version: 1.20.2-4.5.1
• Does the issue persist with only ETF installed?: No, requires both 1) ETF with FreshAnimations resource pack 2) Iris with ComplementaryReimagined r5.0.1. Removing or altering any of those two conditions would resolve it.
• Have you checked the FAQ in the Readme, or Discord, to see if it is a known issue?: Yes

Other information: ComplementaryReimagined r5.0.1 shaders seems to have lower performance when displaying entities on screen compared to its r2.3 version, overall, and ETF seems to exacerbate that a lot. Some results:

Shader Ver | PBR?     | ETF Ver | FreshAnimations?  | FPS (Avg) | FPS (Facing Entities)
---------------------------------------------------------------------------------------
r2.3       | Enabled  | 4.5.1   | Enabled           | 50-60     | 50-60
r5.0.1     | Enabled  | 4.5.1   | Enabled           | 50-60     | 5-10
r5.0.1     | Disabled | 4.5.1   | Enabled           | 50-60     | 30-40
r5.0.1     | Enabled  | 4.5.1   | Disabled          | 50-60     | 30-40
r5.0.1     | Enabled  | Removed | N/A, ETF Required | 50-60     | 30-40

I have a 2020 iMac with a Core i9 and 5700XT and am aware there are likely thermal constraints. I am not ruling out that I am approaching a performance bottleneck of my computer and the combination of this specific shader and ETF is stressing the system too much, but it just seems like to steep of a performance drop to purely blame hardware. I did contact the ComplementaryReimagined team via Discord, and as with all performance issues I've had in the past, an admin responded within just 1-2 minutes saying it's likely my hardware setup without really looking into it. In the past, some unrelated performance issues have definitely been resolved in newer revisions of their shader pack, so I am not sure if they are just giving a boilerplate response.