I have a huge schema (500x500x200) that I'm trying to paste into a single player world. After about 5 minutes, the game just gives up and crashes. Is there a way to do it in stages? Or break up the schema externally?

MC 1.17.1
litematica-fabric-1.17.1-0.0.0-dev.20210713.103711
malilib-fabric-1.17.1-0.10.0-dev.24

Try the latest version (2021-09-06), I changed the paste task to work in per-chunk pieces in that version.

Yeah, it works great now! Should have checked for an updated version first.