I think its common to external editors, Topaz does it too. They create TIFF files because its the one file type I guess anything can work with and it retains a lot of information. What I do is work on the image in the external editor, save it back to my library, and then export it to a full size, high quality jpeg. Then I delete the huge TIFF file and put the jpeg back in its place. Takes up about one tenth the space. This wouldn't make sense with a non-destructive editor like Aperture or Lightroom, but since you can't do much with those Nik created files once you've close the Nik editor, no harm in trashing the huge file and just saving it in a more economical format. I seriously thought about ditching all of the external editors until I'd worked that out. I'll import a RAW file into Aperture and it'll take up about 11-12 mb and I can create as many Aperture versions and edits as I want without taking up any additional space (since all the program is saving for each is the settings - not the whole image). Once I go to an external editor and it creates a TIFF, I'm looking at a 60-70 mb file! But once I save it as a jpeg and replace the TIFF with the jpeg, its down to about 5-7mb. Still another file beyond the original RAW file, but much more manageable.I just wish you didn't end up with such large-sized image files when you get back to your library. I guess that is just something you have to expect when using the Nik stuff.