Lag and more glitches specifed..

I Downloaded the MCPE 0.16.0/0.15.90 Beta and i noticed an extreme amount of lag and my hand ingame and anything i hold is invisible! whenever i open any menus, i get a black screen for about 5 seconds then im taken back to prev menu..... any time i pause the game i cant tap anything and am forced to restart... fix plz!

Im on an Insignia Flex 8 Tablet Running Quad Core and Android 5.0.1