How to reproduce:
1. Open the attached project
2. Open the "Nested" scene
3. Add any component to Assets/NestedHierarchy/Tile prefab, Unity freezes for a minute

Expected result: Unity adds a component and updates every tile in the scene in seconds.
Actual result: Unity freezes for a minute or more.

Reproducible with: 2017.3.0a3, 2017.2.0b6, 2017.1.0p3, 5.6.3f1, 5.6.0b1, 5.6.0a6.
Regression introduced in: 5.6.0a6.
Not Reproducible with: 5.6.0a5, 5.6.0a1, 5.5.4p2.

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Fixed in 2018.1.0a1