How to troubleshoot slow shutdown?

When I shutdown my computer there is some annoying delay, it takes about 5-10 seconds in 13.10 when in the previous version it was almost instantaneous.

During shutdown I press escape to cancel the splash screen and can see that a big part of the delay is after "Asking all remaining process to terminate...", and then there is "Killing all remaining processes". I have filmed the process with my video camera to check which processes had to be killed, but they didn't chat anything to the terminal.

I previously had this same issue in 11.10, and I resolved it as answered here, however this did not work for me in 13.10.

How to identify the cause of delays in the shutdown process, and fix them?

Turn on reporting for misbehaving applications:

1. Open /etc/init.d/sendsigs in your favourite text editor, with root privileges (e.g sudo vi /etc/init.d/sendsigs or gksu /etc/init.d/sendsigs). Search for the line #report_unkillable and uncomment it (i.e. remove the # tag). Save the file.

2. Make sure that apport is enabled: Edit the file /etc/default/apport so it reads enabled=1. (If it was enabled=0 then reboot, so apport can start.)

3. Shutdown.

4. Upon the next boot apport should come up with a message telling you that there was some kind of problem with a program. That is the one causing the delay. And there should be a crash report in /var/crash . (If apport doesn't report the name, then just look in the crash file, in the end of the file there will be something like Title: MISBEHAVING_PROGRAMNAME does not terminate at computer shutdown)