subj. Discussion is here: http://vk.com/topic-38024296_27847833?offset=20
Useful discussion :P We probably should keep a projection in the image colorspace, not the layer colorspace. Also, I want to add the possibility to add layers in a different resolution from the image (for comic book inking, and for vector layers), and that will in all likelihood be slow as well, unless the node projection is in the image resolution/colorspace.
Ack.
This bug is fixed in master