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  1. Qt
  2. QTBUG-8490

Updating complex parts of a widget instead of all of the widget many times a second takes a lot of CPU on Mac OS X

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: P2: Important P2: Important
    • 5.0.0
    • 4.6.2
    • Core: Event loop
    • None
    • macOS

      This use case is to update a widget containing close to 100 meters where the meters update many times a second.
      To optimize the performance, only the part of the widget that is changed is updated. When this is done, the application uses from 50 - 100% CPU on Mac.
      The same code on Win uses close to 0% CPU.

      When updating the entire widget every time the CPU load is considerably lower.
      This contradicts the performance gain you should have by not updating everything all the time.

        1. meter_test.zip
          4 kB
          Nokia Qt Support
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            richard Richard Moe Gustavsen
            sanonymous Nokia Qt Support (Inactive)
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              Created:
              Updated:
              Resolved:

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