If searching takes too long, the obvious solution would appear to be to get a faster computer (or many parallel computers). Unfortunately, this often does not help.
The exponential growth of search trees can outrun computer power. In chess, a computer 1,000 times as fast yields a benefit of only two plies deeper search in the same amount of time; a computer 1,000,000 times as fast yields four plies.
The Moral:
Use knowledge about the problem domain to reduce the size of the search space.