QTableView - scroll performance changed from 4.0 to 4.1 and 4.2

[budul]

Hi all,
i need to move my code from 4.0 to 4.2. But unfortunately found big problem in performance when scrolling in QTableView with many custom widgets loaded in the table and in "Edit Mode". One can easily reproduce this phenomena with use of QT4 example - SpinBoxDelegate under Item View examples. Just modify main.cpp from:

QStandardItemModel model(4, 2);
 
for (int row = 0; row < 4; ++row) 
{
     for (int column = 0; column < 2; ++column) 
     {
          QModelIndex index = model.index(row, column, QModelIndex());
          model.setData(index, QVariant((row+1) * (column+1)));
     }
}

QStandardItemModel model(4, 2);

for (int row = 0; row < 4; ++row) 
{
     for (int column = 0; column < 2; ++column) 
     {
          QModelIndex index = model.index(row, column, QModelIndex());
          model.setData(index, QVariant((row+1) * (column+1)));
     }
}

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to

QStandardItemModel model(400, 200);
 
for (int row = 0; row < 400; ++row) 
{
    for (int column = 0; column < 200; ++column) 
    {
       QModelIndex index = model.index(row, column, QModelIndex());
       model.setData(index, QVariant((row+1) * (column+1)));
       tableView.openPersistenEditor(index);
    }
}

QStandardItemModel model(400, 200);

for (int row = 0; row < 400; ++row) 
{
    for (int column = 0; column < 200; ++column) 
    {
       QModelIndex index = model.index(row, column, QModelIndex());
       model.setData(index, QVariant((row+1) * (column+1)));
       tableView.openPersistenEditor(index);
    }
}

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I know it takes so looong time to load all the widgets to the table, but this is not big issue for me, because it starts only once.
Anyway there had to be a significant change in QT from 4.0. Because with 4.0 the same code had no problem with sroll at all.

Any ideas? Did i miss something?

Thanks a lot!
B.