Lag sipkes or game freezing every 15 or so seconds

So, the game freezing every 15 seconds or so is a big problem, no matter how low i get my graphics or turn off the wifi or anything, the game just keep on freezing, and whats more annoying then that is the player freeze and the screen but the mobs and other stuff keep going while im freezing, im writing this complaint after ive been blown up by a creeper in a cave while i was frozen, please fix this its so annoying and at this point the game is really unplayable, like REALLY UNPLAYABLE, i lost 3 hardcore world because of this.