One of Explorer’s features is to display a thumbnail of images and the first frame of the video when seen in Thumbnail view. Explorer can either create it when you access the folder or fetch it from the thumbnail cache. Fetching thumbnails from the cache is significantly faster, but will consume a lot of hard disk space, especially if your system is chock-full of images and video.
Navigate to:
HCU\ Software\ Microsoft\ Windows\ CurrentVersion\
Explorer\Advanced
Set the DWORD Value DisableThumbnailCache to 1 if you are low on hard disk space. Otherwise, it makes sense to leave it at zero—the thumbnail cache can indeed be useful.
