I upgraded our web server operating system from Ubuntu 17.10 to Ubuntu 18.04 tonight.

     I replaced our previous database, MySql 5.7 with MariaDB 10.3.  This was not entirely smooth owing to the existence of mysql in the NIS database conflicting with the local user that the install script wanted to create and NOTHING in the error messages gave a clue as to why ti was failing.

     When all was said and done, this shaved about 150ms off of the time to first byte and about half a second off our total page load time so it was worthwhile.