I run firefox on an ubuntu 9.04 computer. I monitor power consumption with powertop. Firefox is the worst culprit when it comes to battery waste. Sometimes, out of the blue, it keeps running at >90% CPU utilization. At least that is easy to detect because the computer gets hot.

But more often than not, Firefox keeps the CPU busy in state C0, and even if its CPU usage is small, the CPU just can't go into power savings mode. Firefox can account for 3-10 watts of usage on a regular session.

The problem is, even if I close all the windows/tabs and leave only a static document in the only window left, firefox keeps using the CPU. The only solution is to kill it and restart it. It is frustrating.

Whenever I want maximum battery life, Firefox is killed first, followed by the wireless card (using the physical switch). By doing these two things I can expand battery life by 50% (assuming Firefox is not misbehaving my laptop uses ~ 15 watts, 10 without firefox and wireless, and screen at 30% brightness).

-dmg

* gnus. The _best_ email reader.
* remember, along with org make your life simpler
* flyspell, for those times my fingers misbehave
* auc-tex mode for writing latex
* w3 for those times you have to cut and past nicely formatted web pages into a buffer
* org-mode again, for table editing
* calc, for a very powerful calculator
* tetris to kill time
* dired mode for browsing directories and acting upon files
* edit-env for modifying environment variables in the running process (and future children)
* mpg123 to play your mp3 collection
* igrep: very nice grep, better than default one.
* yasb: switch buffers via regular expression.

Some nice tricks:

* make-frame-on-display. Start a window of a running process in another Xserver (including a remote one)
* emacs-client -n. Load file in running emacs (in server mode) without waiting

* Being able to run emacs in a Nokia N810! With remember and org this is a killer application.

--dmg