Query on Binary XML is supposed to show an improved performance , but it is not the case here.
why is that so ?
Sorry, I hardly see any proof.
Do not rely on the cost figure to decide whether a query is performant or not.
But first and foremost, both queries are obviously different. The first one works on a structured content (using a wrong approach btw), the second performs a simple pattern search.
They're not comparable.
If you want to use XMLType, then you'll have to adapt your queries so that they treat the content as XML, and not a bucket of random characters.
where xmlexists (
, 'tig' as "pat"