SLING-2457 fixed the ACL issue with super type lookups, but at the cost of creating a new admin resource resolver for every super type lookup. If an inheritance chain contains multiple super types (N), a single call can trigger the creation of N admin sessions. Often this also happens for a number of resources per request, depending on the application, so you might end up creating many Jackrabbit JCR sessions per request. While creating a resource resolver / session is cheap, having too many at the same time has a big performance impact on the read performance due to increased concurrency in the JCR repository layer.
- implementation in ResourceResolverImpl.isResourceType() and getParentResourceType() 
A simple fix could be to cache a single admin resolver for the duration of the resource resolver containing it and reusing it for subsequent isResourceType() calls.
Another improvement could also be to cache the isResourceType() lookups - if this is a typical short-lived request resource resolver. Within a request resource type hierarchies are unlikely to change and should probably be stable (and with Jackrabbit Oak the session won't refresh anyway). The cache would simply be a map of "resource type" => "is also this resource type", so that the super lookups don't have to be done again and again. Often an application might iterate over a tree of data and looking for the same resource type again and again, so the hit rate for the cache will be high.