Minecraft demonstrates that (despite its possibly-inefficient coding) unique voxel based geometry is cpu heavy, and to pretend otherwise is fraud. From the outset it's obvious that recursion is affording the 'infinite' tag for this technology.
Interestingly this technology or even this idea isn't anything new. A nice way of summarising it is 3d fractals, sure it's infinite and richly detailed. But it's the same thing over and over again.