Windows Vista shows preview of a minimized window in the taskbar when you hover your mouse cursor over its icon in the taskbar. This requires extra processing power. If your computer is older or slower one then you can disable window thumbnail previews. Here is how :
- Right click anywhere on the taskbar and select Properties from the menu
- In the Taskbar and Start Menu Properties window, select the Taskbar tab if not already selected.
- Uncheck the checkbox labeled Show window previews as shown,
- Click OK button to save the settings.