How to reproduce:
1. Open the attached “IN-72831“ project
2. Open the “bug_primitiveid” scene and enter Play mode
3. Press the “Stats” button in the top-right corner of the Game view
4. Take note of the frame rate displayed in the Statistics window
5. In the Project tab, navigate to “Assets/ExampleCode/” and select the “Unlit_NewUnlitShader” Material
6. In the Inspector, select the “Shader” drop-down and choose “Tesselation/BUG_SV_PrimitiveID”
7. Repeat step 4
Expected result: The frame rate does not change when the shader is changed
Actual result: There is a significant drop in frame rate when the tessellation shader is applied (160FPS to 100FPS)
Reproducible in: 2021.3.37f1, 2022.3.26f1, 2023.2.19f1, 6000.0.0b16
Reproducible on: macOS 10.15 (Intel), macOS 11.7.2 (Intel), macOS 12 (Silicon)
Not reproducible on: Windows 10, Windows 11
Notes:
- Also reproducible in Player
- Not reproducible with OpenGLES3, OpenGLCore, and Vulkan graphics APIs
- The shaders failed to render using Direct3D11 and Direct3D12