Ubuntu 21.04 Power mode

This link https://gitlab.freedesktop.org/hadess/power-profiles-daemon is providing all the details required for command line.

Installation Steps

git clone https://gitlab.freedesktop.org/hadess/power-profiles-daemon.git
cd power-profiles-daemon
meson _build -Dprefix=/usr
ninja -v -C _build install

to know which profile is active run below command

gdbus introspect --system --dest net.hadess.PowerProfiles --object-path /net/hadess/PowerProfiles

some of the result

  interface net.hadess.PowerProfiles {
    methods:
    signals:
    properties:
      readwrite s ActiveProfile = 'balanced';

to set the Performance mode run the below command

gdbus call --system --dest net.hadess.PowerProfiles --object-path /net/hadess/PowerProfiles --method org.freedesktop.DBus.Properties.Set 'net.hadess.PowerProfiles' 'ActiveProfile' "<'performance'>"

Available Profiles

1. power-saver
2. balanced
3. performance

Try this command and reboot and see for the persistence. If the profile is changing back to what you dont want, then put the above command in startup command list.

Actually there is an easy way which does not require any compilation or script writing.
Simply put the command powerprofilesctl set performance into your Startup Applications or into a file that will be run during startup.