CPU 100% when try do something in MCPE :/

Hi there.

My computer have power: I7 4720 HQ 2,60 GHz 8 Gb RAM graphic 4 Gb, buuuuuut minecraft after playing 20 hours and creating some stuff keep lagging all the time. 100% on that kind CPU is stupid and not logic. Please say what i need to do, to play this game?