On: Why have CPUs been limited in frequency to around 3.5Ghz for so many years?

[shasta]

Multiprocessing doesn't help with TeX because compiling it is an inherently linear problem the way it was designed. One can imagine a layout language that sucks less (TeX is very powerful but one of the worst designed languages in existence) that can manage to work on rendering different parts of the document in parallel.

[justincormack → shasta]

Indeed he says that solving the whole document layout optimization is too hard, so much of the rendering of paragraphs could be fairly parallel.