"Creating thumbnails of images is often exhausting and takes time nobody has. And so it seems clever to let PHP do this. Nevertheless there is one hitch: The thumbs are by far not high-quality. They almost always look better if you create them manually.
As you see, it is high time for this plugin! It automatically creates the tiny images and uses an unsharp mask to get the best quality possible. Of course the images are cached, because the unsharp mask needs more CPU-power than the conventional...