Inserting Text into Editor

I have a situation where I have to insert large amounts of text into the editor and it is taking a while to populate the editor with the text. I found that calling InsertText would insert the text pretty fast (can I thread my text building and call InsertText through an Invoke on the window?) but when I call InsertText it moves the cursor to the end point of the insert.

Is there a way to insert text into the editor (without using .Text += since this seems to be really slow for large documents) and have the current insertion point remain where it is and allow the user to scroll while text is continuing to be added?

Hope this question was clear enough.

Thanks