I simply must disagree about performance not being an issue anymore. It seems dishonest the way that argument is put form. Perf does not exist in isolation. Just because people think performance is good enough does not mean performance does not matter
even for stuff like desktop applications. Why? Because all though perf may "feel" fine perf and power are intimately related, and people are starting to care a whole lot about power use.
Remember the faster your code runs the sooner the CPU(s) can go back to sleep. The smaller your working set gets you get fewer trickle writes to the hard drive as you dirty pages. Fewer trickle writes mean longer periods with the disk spun down. Better socket
coding stratatagies can allow the wireles NIC to enter a lower power state more often. etc....
So please stop thinking every computer is a server where the CPU is allways underutilized and there is no power management. Laptop sales are the leading growth driver for the PC industry so until all computers stop running on batteries then perf still matters.