Who says that your laptop has to suffer slow performance to save a little energy? How much your performance or battery life changes depends on your laptop age, battery age, and other programs and settings. Here are some simple steps to help increase battery life while mostly maintaining if not improving performance.
Step 1: Change the Power Plan
Every computer has several energy plans in their power settings. Go into the control panel. Go into System and Maintenance (XP & Vista) or System and Security (7). Go into Power Options. Select Max Battery in the drop box and apply the settings (XP) or click on the Power saver option (Vista & 7).
Step 2: Modify Performance Options
Go into the Start Menu. Right-click computer and go to properties. Go to the advanced tab (XP) or go into "Advanced system settings" on the left side (Vista & 7). Go into the performance settings. Set it to "Adjust for best performance" and apply it.
Step 3: Remove the Desktop Background
For Windows XP, go into the control panel. Go into "Appearance and themes". Click "Change the desktop background". Set it to "none" at the top of the list and apply it.
For Windows Vista, go into the control panel. Under "Appearance and Personalization", click "Change desktop background". Set it to "none" at the top of the list and apply it.
For Windows 7, go into the control panel. Under "Appearance and Personalization", click "Change the theme". Go to the bottom of the list and click "Windows Classic".
Desktop backgrounds are still visualized when windows appear and get moved around and also put some demand on the GPU (& CPU if it isn't strong enough).
Step 4: Happy Power Saving
Hopefully now your laptop will last longer and still enjoy good performance. If you have any other good power saving suggestions, please share it.