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.