"camayakaA float"
GIMP-2.10 uses GEGL as the engine and up until now it has primarily been processing RGBA data of various kinds; and by now GEGL is doing a good job in RGBA. There have also been a few optimized code paths in operations like gaussian-blur for also operating on gray-scale data instead of implicitly promoting and blowing up the data to 4 single precision float components. To be fast for gray-scale operation we want more of GEGLs operations to have gray-scale code paths, or even better be implemented  so that they support any count of components. Code making the number of components dynamic for blurs, arithmetic on layers and the samplers used for among other things rotation and scale have now been added to GEGL.

These changes do not only benefit gray-scale though, it opens up for doing multi/hyper spectral processing, as well as also being the groundwork needed for providing CMYK processing. Experiments in that direction have started in a babl branch where CMYK formats have inverted channels. Including a pixel format with the same name as the title of this post, "camayakaA float" - inverted CMYK with pre-multiplied alpha components.

This is the first public steps towards such support in babl/GEGL; it remains to be seen when it is working satisfactory there before GIMP needs to consider integrating support, in the immediate future though people editing large gray-scale scans in GIMP will likely see improvements as a result of this.