I understand a couple questions (i.e. this) of this nature have already been posted, however no solid solution has been found. From what it seems, Meteor currently lacks of
Meteor doesn't yet support lazy/on demand loading of resources. The feature is on the roadmap as "incremental loading".
In the meantime, have a look at numtel:publicsources and numtel:privatesources, which let you create bundles for lazy loading resources, with or without authentication.