Windows Explorer shows thumbnails for graphic files. In order to view them quickly, Windows saves the previews in the “Thumbs.db” file. These occupy quite a few megabytes of memory, which you can put to a better use. Restrict the amount of space required by the "Thumbs.db” files by modifying the quality and size of the thumbnails in the registry.
For this, start the registry editor with “Start > Run”, “regedit” and “OK”, and there, navigate to the key “HKEY_LOCAL_MACHINE/ SOFTWARE/Microsoft/Windows/current Version/Explorer”.
Create the “ThumbnailQuality” entry with “New > DWORD value”; you can use this to determine the quality of the thumbnail. Open it by double-clicking, and activate the “Decimal” option under “Basis” in the “Edit DWORD value” .
You can then specify the desired quality as a number between “50” and “100” under “Value”. Higher values stand for better quality and a correspondingly higher memory requirement. The standard is “90”. Confirm with “OK”.
Now create the “ThumbnailSize” entry in the same key and this determines the size of the thumbnail. In “Thumbnail Size”, you can assign values ranging between “32” for very small and "255” for very large images.
Delete the “Thumbs.db” files in the respective folders so that the operating system recreates the image database according to the changes made in the registry. It is also possible to completely prevent images from getting saved. For this, open “Extras > Folder options” in the Windows Explorer and check the “Do not save thumbnail views” option in the “View” tab.