Chunks stop generating and commands no longer work after several hours

I used a redstone machine to generate chunks by teleporting the player around the map at near the build limit. After this machine has been running for a couple of hours, chunks stop generating and the game no longer responds to any commands.

The machine is attached as g16.zip.

To reproduce: use a structure block to load the machine "g16" within the spawn chunks or forceloaded chunks. (The machine is 16×16 so it fits within one chunk.)
Start the machine by pressing the button.
The machine will teleport the player

Additional notes: the machine should stress test the terrain generation. Anyone with a fast PC should adjust the speed of the machine by reducing the number of redstone dust in the first pair of hoppers below 30. I used 25 on a dual-core machine, a quad-core machine should be able to manage with 15 or so. Render distance should be 10, maximum frames per second should be reduced as well: I capped my fps to 30.