How to reproduce:
1. Open the user’s attached project
2. In the Projects tab’s search bar, enter “StreamingWorld“ and open the “StreamingWorld.unity“ scene
3. Select the “TIMELINE FOR BUGREPORT“ GameObject in the Hierarchy
4. In the Inspector, double-click the “Playable” field of the Playable Director component to open the Timeline window
5. In the Timeline window, select the padlock in the top-right corner to lock the selection
6. Adjust the length of any of the “Active” segments of the first entry under the “CAMERAS” section of the Timeline window
7. Observe that any changes made in the Timeline window will cause the Editor to freeze for a short time
8. In the menu bar, select “BUG REPORT/Load World”
9. Repeat step 6
10. Observe how the Editor freezes for a longer period when more GameObjects are loaded in the Hierarchy

Expected result: Making changes in the Timeline window does not cause the Editor to freeze
Actual result: The Editor freezes when changes are made in the Timeline window

Reproducible in: 1.7.6 (2021.3.36f1, 2022.3.22f1), 1.8.6 (2021.3.36f1, 2022.3.22f1, 2023.2.17f1, 6000.0.0b13)

Reproducible on: Windows 10, Windows 11
Not reproducible on: No other environments tested

Note: The project contains the Animation Rigging package, where having the RigBuilder component enabled adds a large number of curve bindings. This seems to have a significant impact on performance due to the AnimationMode.AddEditorCurveBinding() method, as shown in the attached images.