Here is a slightly simpler reproducer, even if with way lower times (most probably due to less data attached to the generated hosts).

1. Deploy a Satellite (duh!)
2. Install ansible-collection-redhat-satelite (this is not installed by default on older setups)
3. Create an "ansible" user for pulling the report
   hammer user create --login ansible --password ansible --location 'Default Location' --organization 'Default Organization' --auth-source Internal --mail ansible@localhost
   hammer user add-role --login ansible --role 'Ansible Tower Inventory Reader'
   hammer user add-role --login ansible --role 'View hosts'
   hammer user add-role --login ansible --role 'Viewer'
4. Create 2000 fake hosts
   foreman-rake console

os = Operatingsystem.first
arch = os.architectures.first
domain = Domain.first
org = Organization.first
loc = Location.first
owner = User.anonymous_admin

2000.times.each do |_|
  h = Host::Managed.new(operatingsystem: os, architecture: arch, domain: domain, organization: org, location: loc, owner: owner)
  h.save
end

5. Create an inventory configuration my.foreman.yml (or similar, needs to end in "foreman.yaml")
plugin: redhat.satellite.foreman
url: https://satellite.example.com
validate_certs: false
user: ansible
password: ansible

use_reports_api: true
max_timeout: 3600 
group_prefix: hg_
want_hostcollections: true
want_params: true
legacy_hostvars: true

6. Call "time ansible-inventory -i my.foreman.yaml --list"

On my setup, I get ~45sec for requesting this with "admin" and ~95sec with "ansible" users.
It seems to be stable across 6.9, 6.10 and 6.11 that I have tested here.

> It seems to be stable across 6.9, 6.10 and 6.11 that I have tested here.

6.11 on EL8 does perform better (26s/47s), but it does run on different (albeit actually less performant) HW.

I've merged a small improvement in https://github.com/theforeman/foreman/pull/9223 for the "as admin, it still feels slow"

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