In a AAA game, written in the past 15 years or so the CPU is used to handle I/O (controllers, network, "HDD" etc) and, sometimes, sound (the more modern GPUs ha

In a AAA game, written in the past 15 years or so the CPU is used to handle I/O (controllers, network, "HDD" etc) and, sometimes, sound (the more modern GPUs have low latency cores to work with sound but a plain old PS4/Xbone has too much latency on the GPU to work with sound). On PC the CPU is affecting game performance because there are many layers of data transformation between the userland game and the data that GPU reads and all these are processed on the CPU, but on a console the game writes the native GPU command buffers and surfaces so there is no intermediate processing so CPU is pretty much irrelevant as long as it's fast enough to write couple megs of command buffers per frame and not skip interrupts from the I/O devices.