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Issue ID




Game performance regression with Semaphore.WaitForSignal when rendering a scene

Graphics - LowLevel


Reproduction steps:
1. Open the user's attached project in 2020.2.0a14 or on an older Unity version
2. Open scene "SampleScene"
3. In the Game window, enable Stats on the top right corner of the window
4. Enter Play Mode and note the framerate
5. Repeat the same steps with 2020.2.0a15 or on a newer version and compare the results

Expected result: Framerate displayed in the Statistics is roughly the same in both versions
Actual result: Framerate is significantly lower in newer Unity versions (the difference can be 50-70FPS )

Reproducible with: 2020.2.0a15, 2021.1.0b10, 2021.2.0a7
Not reproducible with: 2018.4.32f1, 2019.4.21f1, 2020.2.0a14

Tested with:
Intel(R) Xeon(R) W-2145 CPU @ 3.70GHz, NVIDIA GeForce GTX 1080, Windows 10
1,6 GHz Dual-Core Intel Core i5, Intel UHD Graphics 617 1536 MB, MacBook Air (Retina, 13-inch, 2019)

- Reproduced on Windows and macOS
- Reproduced using Direct3D11, Direct3D12, Vulkan, OpenGLCore
- Reproduced with built-in RP, HDRP, URP
- From the Profiler data, the issue seems to be reproducible in builds as well

- From the Profiler data, with built-in RP, Semaphore.WaitForSignal or Camera.Render seems to be making the biggest difference

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