I noticed when exploring the config values on Wikidata the config value mw.config.get( 'wbEntity' )
On large items this is horrendously wasteful and will slow down client side rendering/page load time. Germany for instance the HTML has a page size of 2.9MB which is unacceptably big (removing the config property drops the page size down to 2MB).
I am sure this data can be sent to the client in better ways. I doubt many of the values are used by anything and some would be better as data attributes on the HTML itself.
Grepping the code base nothing seems to be currently using it (but I assume some gadgets might be)/ I'd thus recommend killing its use asap.