If you want to Speed Up Windows Explorer in Vista you need to disable thumbnail previews. Thumbnails are reduced-size versions of your pictures and videos. Their role is to allow you to quickly scan and recognize them while browsing your computer. However, each time you use Windows Explorer, it will spend some time to generate them.
First, start Windows Explorer (Windows key + E). Then click on Organize and select Folder and Search Options as shown in the screenshot below.
Go to the View tab and check the first option from the Advanced settings list. This option is called Always shown icons, never thumbnails. When done, click on OK.