I don't think it's much of a waste loading a font at a higher resolution and drawing it scaled. However, you might try experimenting with getting the original size to be a multiple of the size you're scaling to, e.g. to get down to 15pt you might start with 60pt rather than 75 because then you're dealing with scaling the whole thing down by quartering the dimensions, rather than dividing by 5.
Also whenever you scale something down, it has the effect of introducing a certain degree of blur due to approximation of pixels. After you scale you should apply a `sharpen` image-processing pass to crispen it back up again.
Also whenever you scale something down, it has the effect of introducing a certain degree of blur due to approximation of pixels. After you scale you should apply a `sharpen` image-processing pass to crispen it back up again.