Improve initial indexing process by limiting tree traversal

Correct me if I'm wrong, but my understanding is that ModeShape traverses the whole repository tree when building indexes for the first time.
(Having activated DEBUG logging of the index subsystem, I could see all the nodes being processed.)
However, in the case of repositories with a strictly-defined hierarchy, I think that process could be optimized by limiting the traversal to a certain path only, don't you think?
Like the configuration for sequencers, some XPath-based parameter could specify which parent the indexed nodes should be the children of.

Or maybe I'm totally wrong on how ModeShape works – but then I'd still need to find a way to speed up the initial indexing phase, which takes ages on my repository with a 1+ million nodes (if I believe the number of files in the export archives).