Realise this is an old thread - but as it was one of the first results in Google for this topic, I thought I'd update it with my (rather blunt) solution.
1) The script that produces the hardware info is located in /etc/update-motd.d - and is named "30-sysinfo". Remove it (and if you like, the other scripts in there).
2) Edit /etc/pam.d/login and /etc/pam.d/ssh - comment out the line that reads "session optional pam_motd.so motd=/run/motd.dynamic"
Result: Editing /etc/motd now does the right thing - and my system no longer hangs for 30 seconds upon login simply to produce a colour ASCII art banner that tells me what CPU I'm running and what IP I'm logging in from.
