The Windows 7 taskbar displays previews of running programs via some very cool thumbnails. To speed up these thumbnails so that they appear instantly, follow these simple steps:
1. Open Notepad.
2. Copy and paste the following into the new text document:
Windows Registry Editor Version 5.00
3. Save the document as speedy_thumbnails.reg.
4. Double-click the new file to merge it into the Registry.
5. Continue through the UAC prompt and confirm that you wish to perform the action.
6. Restart you computer (or simply stop and start Explorer.exe from the Task Manager).