I am going to make the assumption that the "loading entities" when logging in the game is an update of the build stuff in the area. These entities are most likely cached locally by the client so next time you login you just need to update the entities.

More assumptions: If the zone.xsip file gets updated, every client out there needs to re-download the entities from the game server, causing severe stress to the server. So perhaps the entities should be mirrored on the patch servers as well or be on a separate server.