When using ietFastThumb, creation of the thumbnail is delayed until it is shown on screen. Prior to this a full size image of each frame may be held in memory. For this reason ietFastThumb should not be used unless thumbnail frames are being loaded on demand (or there are not a large number of off-screen frames).
ietFastThumb can improve the quality of thumbnails, particularly when using ImageInfoText and ThumbnailClipping. It cannot be used if you have disabled image caching.
If you use ietFastThumb then you should significantly increase the ImageCacheSize to something larger, such as 200.
// Store images in control as 120 x 100 thumbnails ImageEnMView1.ThumbWidth := 120; ImageEnMView1.ThumbHeight := 100; ImageEnMView1.StoreType := ietThumb;