As each version offers more alerts and connections it usually gives you a little less time on battery. Here I've seen it go both ways but I use the many articles on battery time and NEVER EVER install ad supported apps. Those are the battery time killers.
As to if there is an update, check samsung.com for your model as well as if there is an OTA update by the usual menu.
If you are ready to go off the reservation, hit XDA Forums for such.
I want to upgrade from android 4.3 to lollipop on my gs4 gti9507 but I want to know if there are any performance costs or is the battery life worse?

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