C# RichTextBox lag

I have a richtextbox control on a WPF form. It has SpellChecking.IsEnabled is set to true and VerticalScrollBarVisibility is set to auto, but whenever I type in it it there is a delay before the text appears.

Setting SpellChecking.IsEnabled to fa开发者_运维技巧lse or VerticalScrollBarVisibility to disabled does not stop the lag.

Can anyone suggest a reason why this lag may be occuring, and a possible solution?

Can you give details on your Operating System, hardware, graphic board, or any other thing that maybe related to your performance?

You should turn off unneeded services, anti-virus, and use StopWatch to see what is going on.