Info page performance with larger memberships

On larger lists (~1000 members), the Postorius per-list info page takes upwards of 40 seconds, with a CPU-pegged REST runner in Mailman3-core processing requests to get every list member sequentially.

I think this is a bug on the Postorius side in how it is accessing the REST API, particularly because individual member info doesn't seem to be needed to render this page.

I've tracked that the time is all taking place in mailing_list.get_member(my_email_address) but haven't dug deeper than that: https://gitlab.com/mailman/postorius/blob/master/src/postorius/views/list.py#L195

Versions: Mailman 3.0.0 Postorius 1.0.1