Comment 4 for bug 101905

Sorry, but I have to confirm the "bug".

"...the emacs-extra package turn on zone mode..." (not emacs-common itself) : true.

but uninstalling emacs-extra is NOT a solution! emacs-extra is otherwise full of good things, as one can read from the many features enabled by
/usr/share/emacs/site-lisp/emacs-extra/emacs-extra.el

and, no, turning zone on is not done in the user's .emacs file, which is almost empty after install, but in the system customizations, more precisely in the file above. Actually, references to "zone" customizations, after removing the unrelated "time-zone" things, are disseminated everywhere!
(do grep "zone" /usr/share/emacs*/*/*/*.el | grep -v "time" to see this...)

To conclude, that's the lines
--------
(when (>= emacs-major-version 21)
[...]
  (require 'zone)
  (setq zone-idle 300)
  (zone-when-idle 300))
--------
in /usr/share/emacs/site-lisp/emacs-extra/emacs-extra.el
which cause the automatic loading of zone. One needs to cut them out at every reinstallation.
I confirm that I needed to do it just today, after a fresh Ubuntu dist-upgrade (to emacs22)
No telling, in a poll if one should remove these lines in the 'standard' emacs-extra.el file, I vote 'yes', for the reasons very well described by Tim Jones in his posts, and because zone is just not useful.

PS: I suspect a bug in zone itself. It looks like, if zone is up and running while the system is awake, it takes small resources, but if it is working while screensaver is on, then it takes much more resources... I don't know, but it looks like zone relyes on the pauses for drawing to screen, and, if not occurring because of screensaver, it takes much more cpu.