How to reproduce:
1. Open the user's attached "913013-URPSaveIssue.zip"
2. Select the "ForwardRenderer" Asset in the Project window (Assets/Settings)
3. Expand and collapse the Renderer Feature in the Inspector window
4. Observe the Inspector window

Expected result: No freeze in the Editor when expanding/collapsing the Renderer Feature with the arrow in the Forward Renderer Asset
Actual result: A short freeze occurs in the Editor when expanding/collapsing the Renderer Feature with the arrow in the Forward Renderer Asset

Reproducible with: 7.5.1 (2019.4.11f1), 8.2.0 (2020.1.7f1), 10.0.0-preview.26 (2020.2.0b4)
Could not test with: 4.10.0-preview (2018.4.27f1) - Forward Renderer is not supported

Notes:
- There can be seen a spike in CPU usage in the Profiler (Editor mode) when expanding/collapsing the Renderer Feature with the arrow in the Forward Renderer Asset
- The issue is not reproducible if the Renderer Feature is expanded/collapsed by pressing on the Renderer Feature's name