Here in serbia it is not that bad if you can use "land" internet. if you go to mobile data, after few GB it gets insane. there are some options that give you 100gb mobile "home" internet for 15-20Eur with good speed. Where you have cable internet, speeds are not greatest but for 15-20 eur you get unlimited data for a month.
I never thought hive would be data heavy. maybe photos? i seen years ago that Opera had data saving option for mobile browsing. never used it, so no idea how it works.
I was hammered by costs when I was in Serbia last year - I am used to being "in Europe" :D
I don't know how to check it, but it is pretty heavy from my understanding. I think it is because it reloads pretty much everything each time.
you know what is the first thing we do when we get close to the border?
we turn of mobile internet :D my friend got 150 eur bill for one day in Slovakia. forgot to turn of mobile data transfer in roaming.
Best thing is buying local sim card and get few GB internet for 3-5 eur.