Reproduction steps:
1. Create new project and import Script2
2. Create an empty Gameobject and add the Script2 component
3. Make the Script2's array be 10,000 in length
4. Turn the Gameobject into a prefab
5. Press randomize on the prefab instance in the scene (creating 10,000 prefab overrides) and save the scene
6. Open the prefab, then delete the Script2 component
7. Save and exit the prefab editor
8. Observe the performance of the original prefab by moving and undoing

Expected result: Unused data gets cleared
Actual result: Prefab retains unused, unreachable data slowing down performance

Reproducible with: 2018.4.28f1, 2019.4.11f1, 2020.1.8f1, 2020.2.0b6

Notes: Seems to also be caused by:
- Commenting/removing the array in the script.
- Changing the array length in the prefab
- Changing the array length in the instance
- Removing the script in the instance (creating a removal override)

Array size should be increased if prefab performance difference is not noticeable