We don't use component interfaces much (although we should, I agree). Nevertheless, we noticed recently the same delay in a large assembly. We recently moved from WF3 to WF5, so I assume it's WF5-related. We decided to add the option comp_interface_placement interface_to_geom, which resolved the problem.
We didn't test it in Creo2.
Met vriendelijke groeten,Best Regards,