In Hibernate Search 5 we fixed some classloading issues and highly improved the overall modules structure to avoid leaking any unrequested dependency and minimize classloader exposure to each sub-component as needed.
I expect this to also improve performance - for example - of Hibernate classpath scanning.

The modules built in WildFly for Hibernate Search still mimick the structure we had in Hibernate Search 4, we should improve this to get the same shape as the modules we build during a release of Hibernate Search 5.