Test world shenanigans

UPDATE
I know what's going on. There are infinite of every block in the world.
Also, breaking a furnace in the world crashes the game and breaking redstone makes its brightness go to off and scroll-clicking the double slab blocks gets mostly tile.stoneSlab.slabName.name such as tile.stoneSlab.cobblestone.name and the wood slabs texture is a purple and black checkerboard and a=has the name tile.stoneSlab.wood_old.name.
Also, summoning PrimedTnt near the two TNT blocks (what's the difference between them?) creates endless TNT (lol). Good thing my computer's so powerful 😉

Walking into one of the pressure plates in the Test world Throws up tons of items, creates game-stopping lag and causes Minecraft to stop responding; so badly that I alt+tab then close the game externally. I'm pretty sure pressure plates shouldn't throw up that many items.
The screenshot shows what happened when I threw an item into it (the screen is gray as Minecraft stopped responding)
The same thing happens with stone pressure plates.