Steps to repro:
1. Create the new project;
2. Add a Cube and a Plane gameobjects;
3. Select added Cube and Plane and mark Cube and Plane gameobject as Static;
4. Select Directional light and change its type to Area (Baked only);
5. In the Lighting window (Window>Rendering>Lighting) click New Lighting Settings button;
6. In the Lighting window change the Lightmapper to Progressive GPU;
7. In the Lighting window press Generate Lighting button;
8. After the GI bake is done open the Editor.log file and search for the following string: "[PathTracer] Loaded OpenCL shaders in X secs -> Timestamps:" where X is a current OpenCL shader loading time;
9. Compare the shader loading time between different Unity versions.
Expected result:
OpenCL shader loading takes reasonable amount of time.
Actual result:
OpenCL shader loading time has become significantly slower. Below are the results obtained in different public Unity release versions:
2022.2.0a1 (30debfae6b27) - 32.748 sec
2022.1.0b1 (aa8da40855d9) - 33.853 sec
2021.2.7f1 (6bd9e232123f) - 35.860 sec
2021.1.28f1 (f3f9dc10f3dd) - 27.888 sec
2020.3.25f1 (9b9180224418) - 32.336 sec
2019.4.34f1 (6a9faed444f2) - 21.392 sec
2018.4.36f1 (6cd387d23174) - 9.912 sec
Regression introduced in-between Versions 2018.4 and 2019.4 (shader loading time became 2x slower if comparing with 2018.4) and in Version 2020.3 (shader loading time became 3x slower if comparing with 2018.4).
Notes:
- Reproducible in Versions 2022.2.0a1, 2022.1.0b1, 2021.2.7f, 2021.1.28f1, 2020.3.25f1, 2019.4.34f;
- Reproducible on Windows with NVIDIA GeForce RTX 2080 GPU; Not reproducible on macOS;
- Reproducible only when doing the first GI bake in the new project, not reproducible for the subsequent bakes.