Ok, i think that there's a 3G related high power consumption. This morning i've activated the starving kernel but i have a reboot when viewing a video, so i can't do a comparative test because the standard kernel settings were loaded for about 2 hrs.

Anyway, yesterday i have monitored through ssh with top the system activity during the 3G Internet Connection + Chat enabled. I noticed that the big activity occur during the start of the connection. So i think that even without doing nothing a big drain occur when the phone intercepet the chat that i do on PC, saving it on conversation, don't found other explanation. I must do a test during the weekend to see if this is the reason.