As many may already know, proprietary nvidia
drivers for Linux are far from being perfect, with many options limited or even not present at all. One different case is PowerMizer performance mode, which is present in Linux driver, but its value gets purged after every system reboot and returns back to "Auto".
In order to fix that it's necessary to create systemD unit that will enroll new setting every time the system is booted. To do that make sure first that your systemD user configuration directory does exist or create one:
$ cd ~/.config/systemd/user/
If instead you get an error saying that the directory does not exist, create it by typing:
$ mkdir -p ~/.config/systemd/user/