Last modified: 2014-10-14 19:55:50 UTC
For starters, SpecialWikibaseQueryPage has no caching. It's also apparently a wheel re-inventing, subclassing SpecialWikibasePage. Not anything to do with QueryPage in core. Which has marking things as expensive. Caching. Yada yada
Is not related to the Wikibase Query functionality.
Subclassing like this is also bad design wise