Steps to reproduce: 1) Enable spell checking: this.radRichTextBox1.IsSpellCheckingEnabled = true; 2) Set the Text property to some value: this.radTextBox1.Text = "Sample text"; 3) Try deleting the text from the RichTextBox by holding down backspace or the delete key Expected result: See the characters you are deleted one by one by holding the delete key Actual result: The RichTextBox seems to pause, and can not be seen which characters are deleted