Massive lag!

Xperia Z5
The game lags horribly most the time. Especially in the nether. And when looking towards a forest that's full of trees. Or when looking at a bunch of mobs (especially the animal farms). Getting 15-35fps most the time on infinite worlds. I don't think a 2.0ghz octane core cpu and 3gb of ram aren't good enough for MCPE. Or are they?