Featurerequest: Support really big epubs

[Glog78]

from https://github.com/godotengine/godot-docs/tree/master i wanted to open https://nightly.link/godotengine/godot-docs/workflows/build_offline_docs/master/godot-docs-epub-stable.zip

This epub is to slow to be really "usuable" with the following baca settings:

config.zip

I would love to see this solved ( maybe partial loading instead of loading all ? ) because baca supports justify as output , while epy and epr doesn't.