[Logician]

Both approaches have their own pros and cons:

It's true that reading from a text/html file as a include will not put a burden to your server but disadvantages of this structure would be:
1- You need to hack vb more. Dynamic SQL query does not require any hacking in vb, but so as to create a text file, you have to hack newreply.php and newthread.php. Besides you have to hack other vb files if you want a perfect system (like editpost.php or postings.php). What if users edit their posts, or a Mod deletes it/moves it? So as to keep your text files updated you have to cover all gaps which means you'll do a lot of modifications in your vb code. In Db query method you don't touch your vb files in anyway.

2- You can not get detailed data with a text file include: For example you can not easily display how much that post has been read, replied, rated, subscribed. You just display the post itself. however by dynamically querying the server you can get all data you need from any table you need and the entire data will be very uptodate.

IMO SQL method is much better if you want a handy, functional and uptodate info in your non-vb page. Besides it's not so server intensive as you think if you know what you are doing. For example you can query the database according to the table fields that are indexed or you can create new indexes in your db to increase respond time. To get some recent posts to your main page will require around 5-10 SQL queries in your main page which is quite bearable. Please notice that unhacked vb (ver 2) has around 18 queries in main forum page so your site forum page will create half the query load your forum main page creates in your server.

But if you have a busy/slow MYSQL server or a huge post database, you can consider include method over SQL..