Performance decreases significantly when instantiating a Prefab with many children

How to reproduce:
1. Open the “IN-96996_repro“ project
2. Open the “SampleScene“
3. Enter Play Mode and press the Space key
4. Observe the FPS

Expected results: No significant change is seen
Actual result: FPS decreased significantly

Reproducible with: 2021.3.50f1, 2022.3.60f1, 6000.0.43f1, 6000.1.0b11, 6000.2.0a7

Reproducible on: Windows 10
Not reproducible on: No other environment tested

Note:

• Reproducible in Player
• Reproducible after the animators were removed
• The decrease in performance is larger in 2021.3 and 2022.3 streams