ICC profiles embedded in native Affinity documents

[loukash]

Ever since the beginning of using Affinity in 2014, I wondered why my document file sizes are so huge – usually over 1 MB – even though the document is completely blank. It affects all three apps, not just Publisher.
Finally I have figured it out:

• As long as you use the default ICC profiles in Preferences > Color, the document file size will remain "slim", usually under 10 KB for completely blank documents from default presets.
  These are:
  
   
• But I have no use for "U.S. Web Coated (SWOP) v2" in Europe, hence I'd change the default CMYK to ISO Coated v2 300% (ECI) (from eci.org) globally in Preferences > Color because print houses usually want me to avoid more than 300% color anyway, especially with photos.
  Then, however, when I create an unrelated RGB document with a standard sRGB profile, the blank saved *.afpub/afdesign/afphoto file size immediately grows to about 1.4 MB, even though an sRGB profile is usually just a few KB! That's the same file size if I had the default SWOP profile in preferences but assigned the ECI profile to a CMYK document manually. (The actual ECI profile file size is 1.8 MB uncompressed and – wait for it – 1.4 MB zipped.)

Summed up, Affinity apparently embeds the ISO Coated v2 300% (ECI) – or any other non-standard CMYK profile that is set as the new default in Preferences – to any native Affinity document, regardless of color space, even though it's of no use e.g. in RGB space.
An already embeded redundant CMYK profile remains in an RGB document even if I change the app preferences back to CMYK: SWOP and resave the RGB document. It just lives there as junk data.

So, the workarounds for new documents seems to be:

• Keeping the default CMYK preference at SWOP,
  and either assign my favorite CMYK profiles to CMYK documents manually,
  or setting up custom document presets/templates with the respective CMYK profile assigned.

Like that, new RGB documents will embed only the RGB profile they need.

Tested on APu 1.8.4, El Capitan, MacBook Pro 9,1

[loukash]

For illustration, here two blank A4 RGB (!) documents, one created while the ECI CMYK profile was set in preferences, the other one while SWOP CMYK profile was set in preferences:
RGBdoc_ECI_profile_in_preferences.afpub
RGBdoc_SWOP_profile_in_preferences.afpub