Huge lag on Fire tablet that carries over to a connected PS4 (Not Internet connection related)

There is a huge lag on my son's fire tablet, which also carries over to the PS4 when we connect a game together. 

The lag affects pretty much everything , from placing blocks, even to bringing up the menus. 

I can place a row of about 20+ blocks, then all of a sudden they disappear. Also blocks deleted suddenly reappear.

Trying to use a locator map is also extremely laggy and the map won't update for several minutes. 

Also the world generation/draw distance is very laggy.

There is also an issue with dropping and collecting items. Dropped items appear after about 5 seconds, and then fall very slowly to the ground. Collecting items then don't disappear or go into your inventory.