As the computers become faster and faster, the problems become disproportionately larger. The numerical relativity and n-body communities (the latter are people who model the evolution of things like galaxies) routinely have their very highly obtimized Fortran (usually) and C++ (less often) codes run for several months on very high performance or even special purpose (i.e., GRAPE) hardware.

It's just that the really big problems don't get much attention in the popular press or even major facets of the CS world.