having now read through this post: [Pitch] Allow non-resilient modules to hide dependencies to clients and the SE-409 document more[1], i'm a bit less certain the benefits i'd imagined might actually be realized with things as they stand, at least in the context most relevant to me (many-module targets built non-resiliently). IIUC, even with internal imports by default enabled, the compiler still has to (potentially?) load transitive internal dependencies so that type layouts can be computed.
still, i wonder if there aren't some things that might expect to see improved performance with either of these features enabled.