Which is fastest & most efficent when checking for phrases to bna or words to filter?

Arrays. ;)

I disagree. An array will have to be searched entirely.

Keep thinking. This is a common question and there are widely accepted methods for it.

An array makes sense for phrases and similar that you need to InStr or Like for in the received text. A collection makes sense for things you can look up directly such as banned user names.

btree

Do binary trees even make sense in Visual Basic?

Collections might be binary trees, I don't know how they are implemented.