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Bug [2020.3.6f1 + URP10.4.0] Editor GI Chokes CPU with Auto Generate Lighting enabled

Discussion in 'Editor & General Support' started by neurodr0me, Mar 22, 2022.

  1. neurodr0me


    Jul 27, 2016

    1. If Auto Generate is enabled:
    - Performance is fine while lighting is generating.
    - When lighting generation completes, profiler shows GI devouring CPU usage. FPS becomes unusable. This is just while idling and moving around the viewport, not making any changes to the scene. (EDIT: Even if I turn off lighting, effects, etc., or even close the Scene tab altogether, or the Game tab, the CPU load persists).
    - However, if you click Play, in-editor gameplay is perfectly smooth, no issues.
    - Upon exiting play mode, lighting begins to generate again, during which performance is fine. When it finishes, we see the same profiling as above. GI goes nuts.

    2. If Auto Generate is disabled:
    - Performance is always perfect. Before, During, and After manually generating, no issues. In or out of editor, always perfect.


    Per this doc:

    > Note that when you precompute lighting data using Auto Generate, the precomputed lighting data is not stored as Assets in your Project. It is instead stored in memory, and serialized as part of the Scene.

    As far as I can tell, something is wrong with the way the editor is rendering GI in the Scene viewport. When Auto Generate is off, and it's pulling "precomputed lighting data" from "assets in your project", there is no issue, perfect performance. When Auto Generate is on, and it's pulling that data "from memory", something goes wrong in GI processing.

    To reiterate: This is an editor-only problem.

    Please advise :)
    Last edited: Mar 22, 2022
  2. neurodr0me


    Jul 27, 2016
    This problem persists. Does this forum get responses from Unity moderators or should I post somewhere else?