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  1. Qt
  2. QTBUG-140932

Qt6.8.4 compilation of Qt5 project is very slow

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: Not Evaluated Not Evaluated
    • None
    • 6.8.4
    • Build System
    • None
    • windows:
       AMD Ryzen 9 7945HX with Radeon Graphics         (2.50 GHz)
       RAM 32.0 GB (31.7 GB available)
      qt: 6.8.4
      vs: msvc2022
    • Windows

      windows: AMD Ryzen 9 7945HX with Radeon Graphics         (2.50 GHz)

                       RAM 32.0 GB (31.7 GB available)

      1. Compiling qt5 with qt6 consumes resources and is very slow.

      2. Qt5 compilation only takes 10 minutes, Qt6 takes two hours

      3. Qt5 compiles and generates libraries of several tens of MB for pdb, while Qt6 produces 1-2 GB of pdb.

      Is there any way to optimize Qt6 compilation?

       

       

      4、Every time it compiles to a class like the following, it is very slow and consumes a lot of memory and CPU resources ("wbhkplaceoptionorderstore")

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          Dingyuan Yan
        2. image-2025-10-09-19-19-06-738.png
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        3. image-2025-10-09-19-20-54-351.png
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        4. image-2025-10-09-20-19-17-246.png
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          Dingyuan Yan
        5. image-2025-10-09-20-19-31-738.png
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          Dingyuan Yan
        6. image-2025-10-10-11-19-36-064.png
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          Dingyuan Yan
        7. image-2025-10-10-11-39-43-919.png
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          Dingyuan Yan
        8. image-2025-10-11-11-03-14-821.png
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          Dingyuan Yan
        9. image-2025-10-11-11-20-18-593.png
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          Dingyuan Yan
        10. test.7z
          5 kB
          Dingyuan Yan
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            qtbuildsystem Qt Build System Team
            yandingyuan_ Dingyuan Yan
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              Created:
              Updated:

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