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Won't Fix

Votes

0

Found in [Package]

1.8.11

Issue ID

BUR-2586

Regression

No

Entering Play mode in an empty scene takes longer when the Burst package is installed

Package: Burst

-

Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “Assets/Scenes/SampleScene” Scene
3. Enter the Play mode
4. Observe the loading time value in the Console
5. Open the Package Manager window (Window > Package Manager)
6. Install the Burst package
7. After the package is installed, enter the Play mode again
8. Observe the loading time value in the Console and compare it to the previous value

Expected result: Loading times of entering Play mode are approximately the same with and without Burst package installed
Actual result: The loading time with Burst package installed is longer than without it

Reproducible with: 1.8.11 (2021.3.33f1, 2022.3.15f1, 2023.2.4f1, 2023.3.0a18), 1.7.4, 1.6.6 (2021.3.32f1)

Reproducible on: Windows 11
Not reproducible on: No other environment tested

  1. Resolution Note:

    As things currently stand there will always be some overhead to having the Burst package loaded in a project, even if it's not used. So the package should only be included if needed.

    We are working on reducing these overheads, but those changes will mostly likely only land in future versions of Unity.

    The technical details:
    Burst needs to load the entire compiler into memory together with bookkeeping data-structures and caches. This means that more virtual memory is used when Burst is loaded. From the profiling I did, I found that the difference in time-to-enter-playmode was solely due to a forced garbage collection happening (it's part of the enter-playemode process) and the total amount of (live, in-use) memory being visited by the garbage collector just being larger, therefore taking longer time.

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