Do you have MyMenu, Catorize or similar installed (categorisation of your apps list)? There is a firmware bug that makes hildon-desktop keep using 3-10% CPU-time continuously after entering the app sub-menus once or a few times.

You can use htop or conky to find out if this is a problem for you. If it is, hildon-desktop will be continuously (not just short moments) running at more than 3-10% CPU (it should be below 1% when you are just idling).

In general, when things are OK, conky should show you mostly having 250MHz at less than 10% total CPU load when idling (most of that is conky itself displaying its results). If you have more than that for prolonged periods when idling, you have a problem that will drain your battery in less than a day.

I actually think this is one of the main culprits for people having poor battery-life.

To fix the problem, either uninstall MyMenu/Catorize, or run this script every time you have been in the apps-menus:

cd ~/.config/menus
mv hildon.menu tmp
sleep 1
mv tmp hildon.menu

That will reset hildon-desktop and, after a short while, bring it back to normal idling levels.