Sprite sheets in the context of hardware accelerated graphics are essentially a form of texture atlas. As Silverwarrior suggested, packing your images into atlases (as I assume packing into an ASDb does) will greatly improve loading and rendering times as multiple sprites/frames can be loaded in a single image (meaning that you animate texture co-ordinates across an image for each frame rather than selecting a new image)

Also depending on the game you're writing you may be able to implement a caching system that leaves some images to be loaded in the background as the game is running. For example a level in a shootem up doesn't need the graphics for the end boss loaded immediately meaning that the level can be started more quickly. The end boss graphics can be slowly streamed in across multiple frames so as not to cause the engine to slow down (such streaming is how games such as grand theft auto manage giant worlds)

Can you tell us about the capabilities of this sprite engine you're using? what is it letting you do that you need? perhaps we can suggest more modern and maintained engines you can use - They'll give you less headaches in the long run.