Cores
Nearly all our blue label number crunching software has been charged on power units, CPUs, cores and sockets. All of them have had to change to some degree to accommodate VM farms and clouds. The responsiveness seems (to me) have been driven by just how close their nearest competition is.
What's also interesting is the number of stats grads coming out of university pre-loaded with R. A quick browse around also shows a lot of work to link R with things like Hadoop.