Power Savings and Performance Modes on Ubuntu System

You could install Jupiter (http://www.jupiterapplet.org/)

Which adds this this features to your system and allow you to control it using an indicator

Just add the PPA ppa:webupd8team/jupiter to your system using this command

sudo add-apt-repository ppa:webupd8team/jupiter

Update your reposites and install it using these command(s)

sudo apt-get update && sudo apt-get install jupiter

and you are good to go

From a Terminal you can do:

sudo pm-powersave false

to run in high-performance mode.

And to run in powersave mode:

sudo pm-powersave true

Documentation: PowerManagement/ReducedPower

Full disclosure: I feel this really should set the CPU governors, but I'm not actually sure it does that! It might have been a bug on my system that has given me doubt, so it might work just fine for you. I'd welcome feedback from others on this.

Energy save mode in Windows is mostly CPU limiting. You can do that with

sudo cpufreq-set -u 0.8Ghz

or whatever the desired value is. Check minimum and maximum frequency available with

cpufreq-info |grep limits

I do that regularly when using a Laptop on battery.

Display brightness adjustments etc. are up to you.