Well the thing is that original kernel had some weird system inside, and if in text section you put F9XX, then in that place some part of previously written text was printed. That way they didn't have to write 'casts', 'cures' etc. every single time.
I don't understand that thing too good, so I wrote every word 'manually'. That way large part of the files had identical words. Gzip somehow compresses them a lot better and actually my kernel size is 1 kb smaller than the original one, so it didn't modify the TOC. I was looking at the Italian translation, and they got much smaller file too. The biggest size exceeding is about 50 bytes, maybe a bit more.