It's Acorn, which recently upgraded to major Acorn 5 from Acorn 4.4.2... It's not really that different, but 5 is definitely geared toward photo manipulation instead of drawing. A lot of the filters and stuff worked better and quicker, and they added the ability to import Photoshop brushes, but the basic strokes were de-optimized. At the lowest picture depth, I felt like a stroke took slightly longer than usual to process. At 16 bpc depth, it took about a second for each line to draw and at 32 bpc each stroke was like watching a .GIF animation load on a 56k modem, so I downgraded back to 4.4.2, where 16 bpc draws basically real-time (as it should)