How to configure Dragon Dictate so that it does not scan files upon opening?
I was able to replicate that behavior in an earlier major version and to stop it, this is what I did.

Go to Dragon Dictate > Preferences... > Dictation and uncheck the TextEdit check box, as shown in the image below.



Note: This is from Dragon Dictate 3.0.2 and may be somewhat different in version 5, however hopefully this will help to resolve the issue.