public Form1()
        {
            InitializeComponent();

            radSpellChecker1.AutoSpellCheckControl = radChat1.ChatElement.InputTextBox.TextBoxItem;
            Stopwatch sw = new Stopwatch();
            sw.Start();
            IControlSpellChecker textBoxControlSpellChecker = this.radSpellChecker1.GetControlSpellChecker(typeof(RadTextBox));
            DocumentSpellChecker documentSpellChecker = textBoxControlSpellChecker.SpellChecker as DocumentSpellChecker;
            documentSpellChecker.SpellCheckingCulture = EnglishCulture;
            documentSpellChecker.AddDictionary(new MyDictionary(true), EnglishCulture);
            sw.Stop();
            this.Text = sw.ElapsedMilliseconds.ToString();
        }

        private static readonly CultureInfo EnglishCulture = CultureInfo.GetCultureInfo("en-US");
        public class MyDictionary : WordDictionary
        { 

            public MyDictionary(bool forceLoading)
            {
                if (forceLoading)
                {
                    this.EnsureDictionaryLoaded();
                }
            }

            protected override void EnsureDictionaryLoadedOverride()
            {
                using (MemoryStream ms = new MemoryStream(File.ReadAllBytes(@"..\..\en-US.tdf")))
                {
                    this.Load(ms);
                }
            }
        }