People are always asking how the performance of COMSOL Multiphysics® simulation software will improve on a parallel system, especially now that large multi-core desktop computers are relatively inexpensive and it’s easy to rent time on cloud services like the Amazon Elastic Compute Cloud™. It turns out, though, that it’s not always possible to get faster performance just by throwing more hardware at the problem. To understand why, let’s take a conceptual look at computers and the algorithms COMSOL® software uses.