I have been happily using Ubuntu Linux on my laptop computer for over a year and a half now. A couple of weeks ago I noticed that all programs were taking at least 10 seconds to launch. A little Googling led to this Ubuntu bug report which indicated a hostname configuration problem as a possible cause. I opened up the hosts file for editing with:
sudo emacs /etc/hosts
and changed the line:
127.0.0.1 localhost.localdomain localhost
127.0.0.1 localhost.localdomain localhost mudkip
where mudkip is the host name of the computer. And this fixed the problem. Programs now open almost instantaneously. I am not sure why the lack of the host name should cause a 10 second delay in program launching. The discussion on the Ubuntu bug forum seems inconclusive. However, in my case the problem might have been precipitated by me fiddling with the network settings when I was staying at my father's house.