Currently, it save tiled grayscale image as RGB8 which takes a ton of space.
> pingo -s0 -l -notrans -grayscale '.\output\Last Game v04\'
pingo - (28.99s):
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194 files => 486.80 MB - (60.51%) saved
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I don't know if it's possible in comix but AFAIK the Calibre plugins already did this when tiling so they are significantly smaller.