During making it, I was surprised to see how detailing killed some part of the picture, and making it more flat and lifeless. That's why I decided ( with the help of pretty good advices ) to let some area at a speedpainting step. I also like to show the digital painting media at a rought stage, with all this overlays of brush stroke. This made the hair looks lighter, the materials more rigid and the focus more on her detailed face.
The final picture is a bit higher than 5K pixel, and was done only with Gimp-painter. I switched before to Mypaint very often to have access to performance, but with last computer ; a surboosted Dell with an i-core7 processor ; the painting speed is ok with Gimp-painter.So, I can use it from the start to the end on a HD picture. This is a good step of comfort for my open-source professional workflow
The picture under reveal zoomed parts of the picture to give you an idea of the rendering in HD. ( note: a bigger size of the picture is posted on my portfolio.)