How to reproduce:
1. Unzip the user's attached "Repro_910125.zip" project
2. Delete the Library folder from the project
3. Open the unzipped project
4. Open the "Repro_910125" Scene
5. Search for the "Starting Timeline 1" GameObject in the Hierarchy window
6. Select the "Starting Timeline 1" GameObject in the Hierarchy window
7. Open the Timeline window
8. Select the Cinemachine track in the Timeline window
9. Notice that the CinemachineVirtualCamera Component's Status property is set to "Standby" (It changes to "Live" on 1 frame)
10. Drag the Playhead from the start of the Cinemachine track to where it ends (See attached "1279939_repro.mp4")
11. Observe the Memory usage in the Task Manager

Expected result: Memory usage stays the same when CinemachineVirtualCamera's Status property is changing from "Standby" to "Live"
Actual result: Memory usage goes as high as 12 GB when CinemachineVirtualCamera's Status property is changing from "Standby" to "Live"

Reproducible with: 2.6.1 (2018.4.27f1, 2019.4.11f1, 2020.1.7f1, 2020.2.0b4)
Not reproducible with: 2.6.2-preview.1 (2018.4.27f1, 2019.4.11f1, 2020.1.7f1, 2020.2.0b4)