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  1. Qt
  2. QTBUG-87330

QList - double performance drop

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: P3: Somewhat important P3: Somewhat important
    • 6.0
    • 6.0.0 Alpha
    • Core: Containers and Algorithms
    • None
    • core i7-8700
    • Windows
    • 8
    • Qt6_Foundation_Sprint 20, Qt6_Foundation_Sprint 21, Qt6_Foundation_Sprint 22

      This simple code show QList double performance drop for Qt 6

      QElapsedTimer timer;
timer.start();    
QList<QString> list;
int count = 1000000;
for (int i = 0; i < count; i++) {
     list.append(QString::number(i));
}    
qDebug() << timer.elapsed();

      On my machine it prints (release build):

      Qt 5.15.1: 117

      Qt 6.0 alpha: 321

        1. image-2020-10-14-21-15-15-976.png
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        3. image-2020-10-15-02-29-09-196.png
          image-2020-10-15-02-29-09-196.png
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            agolubev Andrei Golubev
            n_r_w n_r_w
            Maurice Kalinowski Maurice Kalinowski
            Alex Blasche Alex Blasche
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              Created:
              Updated:
              Resolved: