"Choosing Dual or Quad Core" Jeff Atwood, speaking of quad-core processors: "But for most software, you hit a point of diminishing returns very rapidly after two cores."

He continues, "It's mostly what I would expect-- only rendering and encoding tasks exploit parallelism enough to overcome the 25% speed deficit between the dual and quad core CPUs. Outside of that specific niche, performance will actually suffer for most general purpose software if you choose a slower quad-core over a faster dual-core."