Do not show thumbnail previews for files in Windows 7

If the thumbnail preview feature is enabled then your computer will slow down. To view thumbnails, you must change the view to Extra Large Icons, Large Icons, or Medium Icons. To do so, open Windows Explorer or click Start button and then click Computer button. Press Alt key to make the Menu Bar appear. Now click on the View tab and do the selection.
Follow these steps to disable the thumbnail previews:
1. Click the Start button and then click Control Panel.
2. If the View by: is Category then click on Appearance and Personalization and then click Folder Options. If the View by: is Large icons or Small icons then click on Folder Options.
3. Click View tab, under Advanced settings:, click to place a checkmark beside Always show icons, never thumbnails.
4. Click Apply and then click OK.

Below is the image for viewing thumbnails for files:
The following image does not show thumbnails for files: