How to reproduce:
1. Open the attached project "Tree_perf__HDRP"
2. Open the Scene "TEST_SCENE"

Expected result: There is no Hold on pop-up window, Scene loads instantly
Actual result: A pop-up window Hold on (busy for xxxxx) SceneView.OnGUI.repaint message appears and then dissapears after 2-4 minutes

Reproducible with: 2020.2.0b3

Notes:
- Wait times of ~2:30 (when Editor UI is unresponsive) are observed while the Scene is loading during scenarios such as: initially opening the project as the Scene view is being loaded or rendered, terrain object being removed and then added back in with undo, Profiler window not being opened
- During wait, computer resources (CPU, memory, disk) are not heavily used
- When issue was originally observed (also using trunk editor 0b3), waits were persistent through editor usage when default profile modules were selected. After removing profile modules except for CPU usage on later repro, wait only seems to occur first time moving from scene > game view