Relying on the nouveau driver and on the vga switcheroo (to get around a change in systemd LP: #1777099) caused increased power consumption, and slowed down the switching process.
Solving the problem in systemd (LP: #1777099), and adding code in gpu-manager and in nvidia-prime to unload the nvidia modules, and to allow the PCI device to sleep, dramatically decreases power consumption.
Relying on the nouveau driver and on the vga switcheroo (to get around a change in systemd LP: #1777099) caused increased power consumption, and slowed down the switching process.
Solving the problem in systemd (LP: #1777099), and adding code in gpu-manager and in nvidia-prime to unload the nvidia modules, and to allow the PCI device to sleep, dramatically decreases power consumption.