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Forget her. Some people who use IntelliScreenX complain it's a battery drainer but I don't think it is. It depends on how you have it set up. If you have it constantly refreshing your facebook, twitter and RSS then obviously that's going to drain the battery faster. A lot of apps/tweaks will drain battery faster the shorter the refresh interval is so keep this in mind. Other than this I don't know of anything else that's known to be a battery hog. Wait for replies from others.
 
To add what's already been mentioned. Themes that rely on widgets are heavy battery drainers. Also Activator, Zephyr, SBSettings, IntelliScreenX are also known to drain battery juice quicker.

Some tips to improve battery life:

-Location Services > System Services > Setting Time Zone - OFF
-Location Based iAds - OFF
-Weather - Local Weather > OFF
-Notification Center > Stocks > OFF
-Bluetooth + WiFi > OFF (when not in use)
-General > About > Diagnostics & Usage > Don’t Send > ON
-General > Restrictions > Ping > OFF
-General > Spotlight Search > Mail - OFF, Messages - OFF

* close background apps (I use an app called "WeeKillBackground Pro" to accomplish this) *

Also MANUALLY adjust Brightness Display (depending on time + current lighting condition) and turn OFF "Auto Brightness."

Last but not least.....ignore the "PMS troll" aka heyyitzmelissa :D
 
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