mmadronicus

Since the issue is really at the get_users level for a site with a large number of users, I’m applying the fix within the theme code, using the pre_get_users action.

For reference, if anyone else encounters this issue, my custom function looks for:

if(is_array($args->query_vars['capability']) && in_array('edit_posts', $args->query_vars['capability']))

and pulls a list of whitelisted user IDs to add to the query_vars like:

$args->query_vars['include'] = [1,2,3,4,5];