using System.Collections.Generic;
using System.Windows;

namespace WpfApp1
{
    public partial class MainWindow : Window
    {
        List<string> list = new List<string>();


        public MainWindow()
        {
            InitializeComponent();

            for (var i = 0; i < 2000; i++)
                list.Add(i.ToString());
        }

        private void Test_Loaded(object sender, RoutedEventArgs e)
        {
            Test.ItemsSource = list;
        }
    }
}