Crash & Tablet turned off.

So heres what i get, I use a item frame, I build a 128x128 on the ground, and when I tried to edit it, It had a little texture glitches, the rainbow one, but it's minor and I keep building. 5 minutes later, I go to my house to see how it looks on the wall, looks fine, so I go back to work on it. Now the glitching is really screwy. Every time I am in that range It acts funny, but in my house it acts fine. Anyways, so I wait 5 minutes out of mcpe, reopen it, go into the world, go to the location, and it takes 15 seconds to break a block, the bugging is horribl, and so I quit. I go back, and in the 3 seconds of me going in it is frozen, then my tablet turns off! I was in a flat world too. Any help? Here's the map if anyone needs to confirm it.