System requirements to boost xapian's performance?

Hi

I'm using Xapian as the search engine for Mailman 3. Having just migrated
our mailing lists from Mailman 2, a key task we need to do is to index the
existing archives for each list.

This is a one-off task for each list so, as we have Mailman 3 running on
AWS compute servers, I'd like to temporarily configure the specification of
the servers so that Mailman 3 and Xapian complete the job as quickly as
possible.

What changes can I make to the specification of a server to best improve
the performance of the indexing? For example, if I throw more cores at
this, will the indexing go faster?

Thanks for any insight/suggestions.

Regards

Philip