Django loads some things lazily but not almost everything. Nearly all your imports should be loaded by the preloaded application and shared across forks (COW semantics aside), and this usually takes up a non-trivial amount of memory. The things that are lazy are usually lazy for a reason - database connections, caching etc.

I believe the i18n system is also lazily loaded and depending on the languages you configure it can take up a fair bit of memory.