If you install vanilla magnolia (no light modules) and create and execute ResourceVisitor to go through all resources observed by the system, you will get number in vicinity of 10K. While it doesn't seem to slow down the system in any way, and might be possibly useful in dev mode (I presume number comes from observation of classpath) where files on classpath can indeed change, i think in production we could reduce the number and thus increase performance in all places that traverse resources (e.g. resfn, definitions app, etc).

Issue was discovered when investigating rendering performance issue in instance with node_modules directory in light module (brought in by use of webpack) and it containing additional 30K files (facepalm). This fact, together with multiple calls to resfn in single template lead to performance issue (traversing of 40K files while searching for resources took approx 2 seconds).