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  1. Qt
  2. QTBUG-140340

[REG: 5->6] Input event delivery performance regression in Qt 6

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    • Linux/Wayland

      There is a big regression in delivering input events in Qt Quick. Attached example in callgrind shows:

      Qt 5.15.18

      ==1572525== I   refs:      15,930,854,003
      

      Qt 6.9.2

      ==1572827== I   refs:      64,225,641,185
      

      And QQuickItemPrivate::itemToParentTransform() seems to jump out. It is the highest cost function in Qt 5.15.18 also, but in Qt 6 this function is now called many more times for a single event than it used to in Qt 5.

      This causes issues with lower end devices where simple mouse moves take 4x as much CPU time as before.

        For Gerrit Dashboard: QTBUG-140340
        # Subject Branch Project Status CR V

            srutledg Shawn Rutledge
            poikelin Joni Poikelin
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              Created:
              Updated: