> spare CPU cycles "Spare CPU cycles" were only a thing back in the 90's, when CPUs ran at a fixed frequency, and it didn't make much difference whether it was

> spare CPU cycles "Spare CPU cycles" were only a thing back in the 90's, when CPUs ran at a fixed frequency, and it didn't make much difference whether it was running useful code or waiting in the idle loop. Nowadays, the frequency and voltage vary depending on whether the CPU is being used or not, so instead of "spare cycles" doing nothing the CPU powers itself down.