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Votes

4

Found in

2021.3.50f1

2022.3.60f1

6000.0.43f1

6000.1.0b11

6000.2.0a7

6000.3.0a1

Issue ID

UUM-100221

Regression

No

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

  1. Resolution Note:

    The issue in the project is that there are over 200 Skinned Mesh Renderers being instantiated.

    Skinned mesh renderers are notoriously expensive, and in this project there are over 10,000 draw calls being emitted when the "Platform" prefab is instantiate. The recommended approach is to use instancing coupled with either Vertex Animation Textures (VAT) or Bone Animation Textures (BAT).

    There are a number of open source tools that allow for VAT creation:
    VATBaker: https://github.com/Mamantenok1599/UnityVATBaker

    And for BAT creation:
    BoneAnimationTexture (BAT): https://github.com/mbmtrex/Bone-Animation-Texture-BAT

    These improve the frame rate significantly and allow for a more characters to be placed on screen without incurring a large performance cost.

    There's an additional article about VAT here: https://medium.com/tech-at-wildlife-studios/texture-animation-techniques-1daecb316657

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