How to reproduce:
1. Open attached project "New Unity Project.zip" and scene "SampleScene"
2. In Hierarchy window, select "physics_step"
3. In Inspector window, set "Physics Step" -> "Simulation Type" to either "Unity Physics" or "Havok Physics"
4. In Hierarchy window, select "FrameLimiter"
5. In Inspector window, set "Desired FPS" to 0 (this will uncap the fps of the Editor)
6. Enter Play mode
7. In Scene view, observe the amount of time it takes for the sphere to move from one column to another (on my machine it takes about 9 seconds)
8. Repeat steps 4-6 but with "Desired FPS" set to 30
9. In Scene view, observe the amount of time it takes for the sphere to move from one column to another (on my machine it takes about 60 seconds)

Expected result: the sphere travel time with different "Desired FPS" is the same
Actual result: the sphere travel time with "Desired FPS" set to uncapped is about 9 seconds and "Desired FPS" set to 30 is ~60 seconds

Reproducible with: 2019.3.0f5, 2020.1.0a20 (0.1.2)
Could not test with: 2017.4, 2018.4 (Havok and Unity Physics not yet implemented) AND 2019.2.19f1 (0.1.1) ("Havok.Physics trial period has ended. is thrown" and the sphere does not move)