Anyway to your question, There is a big difference between Performance and Power Management. Ubuntu performance wise has reduced its boot time and improved its RAM efficiency especially in the recent 10.04 release and the best way to accompany this core performance increase now is to use Lubuntu 10.04 which uses the lighter LXDE enviroment over GNOME.

Unfortunately Power Management is something that I have only seen considered heavily in WattOS which is considerably better than the most power efficient of the top distributions OpenSuse. Power management is not directly about making the computer faster like Performance but about using less CPU cycles, HDD writes/ IO requests and Watts of power to preserve battery life and keep you working on the go longer. Ubuntu as of yet hasn’t set Power management ever as a key release feature or even enabled the full arsenal of optimizations available on Linux to effectively use a battery. http://live.gnome.org/BatteryStatus is a current attempt to provide easy CPU scaling to GNOME users so they can tell Ubuntu to prioritize uptime longevity over performance on battery but this is only a start. Ubuntu needs to do its part too, takeing the time to make its system write less to the HDD (better for SDD’s too) and optimizing its application compiles to certain specific system configurations to shorten CPU cycles until then everyone’s best bet is WattOSPM and learning how laptop-tools works or dare I say it Windows 7.