I've never seen Minecraft's code, but that's how I would do it.
This behaviour is actually quite easy to see if you install any admin mods that allow you to fly faster than the recommended speed.
Since chunk loading is handled on its own thread, the effect in-game is minmal and mostly unintrusive. However, if you pick a direction and fly very quickly - you'll eventually start seeing chunks loading on-screen. The division between the chunk areas in this instance is very easy to see.
I may be wrong, but I believe the chunk size in Minecraft is 64x64x256 (1,048,576 blocks). Obviously there are easy ways of graphing this data to be more accessible and quicker to load (since they aren't 1.04 million unique blocks), but generally speaking that's still a vast array of data to store - so it should give the OP some idea of the clout possible with modern CPU / rendering techniques.
I do get the impression, however, that the OP needs to be a little more familiar with zoning and other techniques for improving CPU load and render performance. I would never subject a game to 15,000 simultaneous object updates - or in fact 15,000 renderable objects in one pass. You should be using techniquies such as view culling, and zoning out areas where updates shouldn't be happening (as mentioned by another poster).
This is the best place to ask such questions though, just don't be afraid to try out some of these things and make mistakes along the way - that's how we all learn