AFAIK the long delay on logout is unity8 dumping core (bug 1535297). Can you provide your unity8.log from when the delay occurred? Or reproduce the bug and provide the log here?
** Changed in: unity8 (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to unity8 in Ubuntu. https://bugs.launchpad.net/bugs/1654308 Title: Logging out of the unity8 session snap takes a long time or sometimes hangs endlessly Status in unity8 package in Ubuntu: Incomplete Bug description: Pat "It consistently takes up to a minute to go from a blank screen to displaying the greeter." kg "as of Jan 5, my log out from unity8-session snap on classic is hanging endlessly, i end up having to reboot" kg's snaps kg@kg-MacBookPro:~$ snap list Name Version Rev Developer Notes address-book-app 0.2+17.04.20161124.2-0ubuntu1 19 canonical devmode camera-app 3.0.0.658 8 canonical devmode chrome-test 55.0.2883.87 19 chadmiller - gallery-app 0.0.67+17.04.20161129-0ubuntu1 10 canonical devmode libreoffice 5.2.3.2 10 canonical - ubuntu-app-platform 1 22 canonical - ubuntu-calculator-app 2.3.1 22 ubuntucoredev devmode ubuntu-calendar-app 0.1.1 22 canonical devmode ubuntu-clock-app 3.8.480 22 ubuntucoredev devmode ubuntu-core 16.04.1 423 canonical - ubuntu-device-flash 3 3 canonical devmode ubuntu-filemanager-app 0.4 10 canonical devmode ubuntu-image 0.5+mvo13 20 canonical devmode ubuntu-terminal-app 0.8 14 canonical devmode unity8-session 1 294 canonical devmode webbrowser-app 20170104-staging 4 canonical - To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity8/+bug/1654308/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp