In Windows 10, File Explorer is able to show small previews for image and video files you have stored on your disk drive. To speed up this process, it uses a cache file hidden in the user profile directory. When a file is cached, File Explorer reuses the thumbnail from the cache to show it instantly. You might want to disable thumbnail previews in File Explorer if they are affecting performance in folders with large number of items.
Here is something you need to know before you continue. If you disable thumbnail previews, file previews will no longer shown in the preview pane. Folders will no longer show a thumbnail preview of their content. Also, in the classic Personalization window in the Control Panel, desktop backgrounds will be shown as icons. In fact, all these changes speed up File Explorer and make your directory navigation notably fast. This is the reason why you might want to disable them.
To disable thumbnail previews in File Explorer in Windows 10, follow the instructions below.
Open File Explorer. You do not need to open any specific location, just run the app.
In the Ribbon user interface of Explorer, click File -> Change folder and search options.
In the "File Explorer options" dialog window, switch to the View tab, and tick (enable) the option Always show icons, never thumbnails. This will disable preview thumbnails in File Explorer.
Now open any folder with images.
It is worth mentioning that there are alternative ways to disable thumbnail previews in File Explorer. One of them is the Visual Effects applet. You can use it as follows.
Press Win + R hotkeys on the keyboard. The Run dialog will appear on the screen. Type the following into the text box and press Enter:
Advanced System Properties will open. Press the Settings button in the Performance section on the Advanced tab.
The following dialog window will be opened:
There untick (disable) the option named Show thumbnails instead of icons and you are done.
If you need to change this option with a Registry tweak, this is also possible.
There is a 32-bit DWORD value IconsOnly. Set it to 1 to disable thumbnails. Otherwise, set it to 0 (this is default setting).
Note: If you do not have that value, then just create it. Even if you are running a 64-bit Windows 10 version, you need to use a 32-bit DWORD value type.
Once you change the IconsOnly value, you only need to refresh your folder in Explorer by pressing F5 to make the changes take effect.
That's it. Now read: How to repair and clear thumbnail cache in Windows 10.