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Votes

0

Found in

2021.3.6f1

2022.1.8f1

2022.2.0a18

2023.1.0a1

2023.2.0a1

Issue ID

UUM-2523

Regression

Yes

Application.targetFrameRate is ignored and causes huge CPU usage

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How to reproduce:
1. Open the attached "TestFPS2019.zip" project
2. Open the "SampleScene" Scene
3. Enter Play Mode
4. Open the Activity Monitor or Task Manager on your OS
5. Select the "<Script>" GameObject from the Hierarchy Window
6. Click once on any of the different buttons labeled "Set xx FPS"

Expected result: No degradation of the CPU performance
Actual result: CPU performance degradation

Reproducible with: 2021.2.0a2, 2021.3.10f1, 2022.1.17f1, 2022.2.0b8, 2023.1.0a11
Not reproducible with: 2019.4.39f1, 2020.3.40f1, 2021.2.0a1

Reproduced on: macOS (Intel) Monterey 12.0.1

Important: User reported the issue on Windows. For macOS (Silicon), the targetFrameRate is already being tracked in:
[https://issuetracker.unity3d.com/issues/m1-max-player-ignores-application-dot-targetframerate]

Note:
- CPU usage sways between ~110-125% of usage on macOS
- Not Reproducible on Windows OS
- Reproducible with these APIs: Metal, OpenGL

  1. Resolution Note:

    This is a documented behaviour: https://docs.unity3d.com/ScriptReference/Application-targetFrameRate.html

    <...> On all other platforms (Mac editor included), Unity ignores the value of targetFrameRate if you set vSyncCount. When you use vSyncCount, Unity calculates the target frame rate by dividing the platform's default target frame rate by the value of vSyncCount. For example, if the platform's default render rate is 60 fps and vSyncCount is 2, Unity tries to render the game at 30 frames per second. <...>

    High FPS is expected to in turn cause high CPU usage.

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