Can you please elaborate on how the TWBX is duplicating the entire database?
When you create an extract on a source, Tableau will effectively 'duplicate' your source into a an extract file but there are a number of advantages to creating an extract. If this approach doesn't work for you though, you may switch your connection to a live connection so it queries the datasource directly. Here's some fun reading on the topic - TDE or Live? When to Use Tableau Data Extracts (or not) | Drawing with Numbers
It MUST be Monday! Face+palm.
You're absolutely right: I forgot to switch it to an extract from live connection! Thank you for your speedy response!