Comment 26 for bug 1893716

Overall the majority of this is now fixed and mitigated with the combination of:
 ubuntu-release-upgrader | 1:22.04.8 | jammy | source
 landscape-client | 19.12-0ubuntu13 | jammy | source, amd64, arm64, armhf, ppc64el, riscv64, s390x
 update-notifier | 3.192.54 | jammy | source, amd64, arm64, armhf, ppc64el, riscv64, s390x

There is still the IMHO valid feature request to pam_motd to not run at all in non-interactive sessions which I'll need to file upstream.

But already in a system with these updates:
ubuntu@login-jammy:~$ dpkg -l ubuntu-release-upgrader-core landscape-common update-notifier-common
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-============================-===============-============-=======================================================
ii landscape-common 19.12-0ubuntu13 amd64 Landscape administration system client - Common files
ii ubuntu-release-upgrader-core 1:22.04.8 all manage release upgrades
ii update-notifier-common 3.192.54 all Files shared between update-notifier and other packages

I now get reasonable results.
Down from 70-80 seconds to ~20-25 => almost down to 1/4 of the time.
At the same time the system is ~16% less busy, so other things running won't stall it that much either and vice versa.

What is left looks as in the test sessions.
This now mostly comes down to the fact that logging in for every command will in general have overhead to spawn the session. For another gain pam_motd can be disabled as shown above, but that does not reduce it to zero overhead - so as explained any mutli-command submitting solution should still - even with the fix - try to use one login for all of them.

# Overhead Command
# ........ ...............
#
    32.50% swapper
    26.67% sshd
     3.53% dbus-daemon
     3.37% systemd
     2.36% run-parts
     2.02% systemd-logind
     1.87% find
     1.85% gdbus
     1.48% cat
     1.47% update-motd-fsc
     1.22% 50-motd-news
     1.17% awk
     1.15% systemd-journal
     1.11% grep
     1.10% bash
     1.05% uname
     0.98% 00-header
     0.93% 91-release-upgr
     0.92% 97-overlayroot
     0.81% 90-updates-avai
     0.80% date
     0.72% cut
     0.68% 50-landscape-sy
     0.62% env
     0.59% ksoftirqd/0
     0.58% 95-hwe-eol
     0.53% stat
     0.51% id