[Prof_Pixel]

I've always used it on Professional setting at 6400dpi (I know that's unnecessarily high)

You appear to be a 35mm shooter from your profile. Saying 64000 ppi is 'unnecessarily high' says it all! Work we did at Kodak suggests that a 25 megapixel file is pretty much the most you can really expect to get from a 35mm image. This only requires you scan at about 2000 ppi. Resolution overscanning can lead to problems. Try scanning at 2000 ppi and see if you like things better.