it doesn't give many actual current details, but http://en.wikipedia.org/wiki/Computational_lithography implies that as of 2006 designing the photomask for a given chip required ~100 CPU years of processing, and presumably that has only gone up.

Etching a 22nm line with 193nm light is a hard problem, and a lot of the techniques used certainly appear to require huge amounts of processing. It's close to impossible to say how much of a bottle neck this particular step in the process is, but based on how much really knowing what is going on in even just simple mechanical design requires lots of simulation I would actually expect that every step in chip design has similar types of simulation requirements.