Its a short term vs long term analysis. If you focus on the long term, programmers are cheaper. Short term, it is easier to throw more hardware at the problem.

Its a short term vs long term analysis. If you focus on the long term, programmers are cheaper. Short term, it is easier to throw more hardware at the problem. The part that makes it difficult to measure is estimating how fast it will run on the new hardware. Usually if you use good algorithms and data structures with an architecture that matches the problem, adding hardware will scale the performance. Mediocre programmers rarely can get this right unless they are lucky.