QCombobox with model with 50,000 rows has large delay on the first-time dropdown

Question

When assigning prepared model having more than 50,000 rows (which performs immediately) to a combobox and trying to press dropdown button, experience a few seconds delay before combobox dropdown list appear. Observe this situation ONLY when FIRST time presses dropdown button in combobox.

Any way to improve performance here?

Answer 1

The key point is combobox by default uses QStandardItemModel to store the items and a QListView subclass displays the popuplist. Investigating QListView properties had solved the problem, details here: https://stackoverflow.com/a/33404207/630169