Mystcraft memory usage

[Typee]

I can't seem to find an up-to-date answer for this:

Does Mystcraft keep a loaded chunk around the spawn in unoccupied ages, and if so, does it do it all the time or just once someone visits this world after server startup?

I wonder if unused worlds are a memory load on the server or just hard drive space.

[Teraku]

They're not loaded at all until someone enters them. They unload when no one is in the world.

[Typee]

Excellent, thank you.