[6ren]

It also depends on how fast the app needs to be, and how far your computer is (e.g. the answer might have been different 20 years ago for the same task) - it would be nice to express the question differently, to make it invariant of these aspects.

For "interesting" tasks (in a research sense), speed is limited by combinatorial explosion. Finding an algorithm/approximation/heuristic that avoids or reduces that is the only real solution - because faster languages, like faster computers, can only give you linear speed up.