@loodjuret. You're probably right, gpu eat less power resulting in a lasting battery, but gtk rendering become too slow for me using compiz.
I think it is related to 8mb mem of gpu used for textures.

@udibuntu
for compiz:

install this deb
sudo apt-get install compiz
sudo gedit /etc/X11/xorg.conf

and add in Device section
Option "ExaNoComposite" "true"
save and reboot


for flash alternative:

sudo apt-add-repository ppa:klich-lukasz/kleewho
sudo apt-get update
sudo apt-get install gnome-mplayer gecko-mediaplayer

open gnome-mplayer settings and tune like the following screenshots:
http://lukaszklich.pl/wp-content/upl...api_output.png
http://lukaszklich.pl/wp-content/upl...5/vaapi_va.png

install this extension for firefox:
http://flvideoreplacer-extension.blogspot.com/
and try youtube