I am not sure what you are planning to do with the custom function. How are domain names relevant?
I have no idea - i am curious.
So, I assumed the custom function would be deployed somewhere local on the server that is also running Neo4J - don' t need to worry about name conflicts.
Regarding the topic:
I am currently testing apoc.periodic.iterate() and apoc.periodic.commit(), have read a ton about memory configuration, bookmarked similiar topics in this forum.
You'll hear from me again next week.
Also i found this comment:
which reinforces taking a look at computing relationships before importing the data.