You have to do it for yourself, official firmware only improves few twicks, improves stability and update the OS.
For manually take care of this tips
1.Off your GPS, WIFI, DATA CONNECTION and BLUETOOTH when not in use. ( they are battery suckers)
2.Use original Samsung charger to charge your tab.
3.Watch your apps which consumes much processor and Ram, after that if they are not important just install them.
4.See your screen brightness, try to increase in daylight and decrease in nights.
5.Use power save option in your tab.
6.Try to charge your tab in switch off mode.
7.While charging don't do task, let it be only charge.
8. Charge only once a day completely without interrupt, rather than always keep on charging for few minutes and then few minutes and so on.. ( You will loose its original capability if you continue doing charging)
Apply all this and you will be charmed