Is it just acs_objects or other tables as well?
You should make sure you have done a vacuum analyze on the
db after inserting some records since it can make a big
difference (even on inserts).
Depending on what you are doing you can probably safely
leave tree_sortkey null. It might be faster if you have only a minimal install (i.e. don't install any additional packages
after the bootstrap since all the fk constraints create
triggers on acs_objects).
What sort of data is it?
