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Fixed in 2022.2.3f1, 2023.1.0a19



Found in



Issue ID




WebGL build times have regressed



Many informal observations of the WebGL build time, in particular the final linker step now take longer than when we first moved to Emscripten 2 in Unity 2021.2

This is especially detrimental in our user's iteration time with development (debug) builds.

The change which likely caused this was the upgrade to Emscripten 3.1.8 in Unity 2022.2

Brendan found this issue,, that concluded compiling with "-sERROR_ON_WASM_CHANGES_AFTER_LINK -sWASM_BIGINT -O1" took linking time from 180 seconds to a couple seconds.

We set the linker options in Platforms/WebGL/WebGLPlayerBuildProgram/WebGLPlayerBuildProgram.cs
in the function SetupPlayerExecutable()
in particular the -O optimization flag is set on line 170

.WithOptLevel(!PlayerBuildConfig.Development && WebGlConfig.optimizeForSize ? "s" : "3")

We need to evaluate the linker flags used, particularly in our development builds to achieve the fastest link time possible, even at the expense of WASM size.

We should make sure that the release (non-development) builds remain with the optimal flags.

  1. Resolution Note (fix version 2022.2.3f1):

    Verified the fix has landed to 2022.2.4f1 with Ubuntu 20.04

Comments (5)

  1. Arlorean

    Mar 15, 2023 13:27

    An empty 3D URP project for me took 393s (6m33s) on 2022.2.6f1 on Windows 11.
    Code Optimization set to "Shorter Build Time" and Development Build not checked.
    Is this to be expected with the fix or is there still a problem?

  2. Andrew-Park

    Mar 02, 2023 02:01

    We are suffering. :(

  3. UDN_98b912b3-c4ea-4f68-ad59-676fdd76a47e

    Feb 26, 2023 23:37

    I don't think this is fixed, or it has regressed in 2022.2.7f

  4. amateurd

    Feb 16, 2023 16:35

    It isn't fixed - still a problem in 2022.2.7f1

  5. DevDunk

    Jan 14, 2023 15:04

    What version will the fix be in? The issue says 2022.2.3, while the comment says 2022.2.4

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