Question

How to speed up a combo box populating speed? Academically speaking, imagine that a combox box has 1 billion records to be presented. How would we maximize the speed of the program.
What other methods could I use instead of a combo box to display data?

Here are the details for my particular question:
I am using WPF event handler

<ComboBox Height="24" SelectedIndex="0" HorizontalAlignment="Left" 
 Margin="146,27,0,0" Name="emoployeeUserNameComboBox" VerticalAlignment="Top"
 Width="198" Loaded="emoployeeUserNameComboBox_Loaded"/>

private void emoployeeUserNameComboBox_Loaded(object sender, RoutedEventArgs e) {
    using (ToolboxDataContext dbToolbox = new ToolboxDataContext()) {
        var query = (from x in dbToolbox.DropDownEmployeesUserNames()
                     select x.UserName).ToList();
        this.emoployeeUserNameComboBox.ItemsSource = query;
    }

The stored procedure above DropDownEmployeesUserNames is defined as

SELECT [UserName],Emp_Number
FROM AdminUser
ORDER BY UserName

It returns 14,257 rows

Answer 1

Combo boxes are meant to contain a limited set of options. If you wish to allow someone to select from 1 billion options, you are better served to use an autocomplete coupled with a button that brings up a popup window that allows efficient searching of the data needed to select an item. I tend to build a pop-up with the following features:

1. A filter mechanism
2. An alpha limiter
3. Paging
4. Recently selected/popular values when there tends to be some congruency in how a user selects values