Question

I have a WPF form which contains 30×30 grid where each grid cell is a ComboBox. ComboBox values and selected value are bound from DataContext. The problem is it goes very slow. I have reworked the form so that it displays textboxes instead of comboboxes (and TextBox is converted to ComboBox on mouse enter) and it work instantly now.

Why are ComboBoxes so slower? Are there any ways to improve massive binding of ComboBoxes?

Answer 1

ComboBox doesn’t use virtualization(VirtualizingStackPanel) by default, you can change the panel used by the control in a very simple way:

<ComboBox ItemsSource="{Binding}">
    <ComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </ComboBox.ItemsPanel>
</ComboBox>

Ref: Improving Combobox Performance through UI Virtualization

That helps a lot in improving performance in case a ComboBox is having thousands of items, not sure how much helpful it will be in your case as having 1000 comboboxes is a lot for UI.

You can also try to put these comboBoxes in a Virtualized panel(like ListBox or directly using VirtualizedStackpanel).

Another thing you can try is to make your ComboBox ItemSource bindings asynchronous using IsAsync property.

I hope you are using ObservableCollection as your ItemSource;