Pointed by the RC thread comment by 'a', I checked the sizes of 4.x to 5.x and 5.x to 6.x TinyCore isos. One extension's growth seemed unwarranted, libjpeg-turbo grew from 90kb to 300kb.
First there's a new lib included, the turbo-specific libturbojpeg, which I think could be disabled if we have no apps using it in the repo. Secondly, the size of libjpeg.so grew from 168kb to 292kb, which seems to mostly be from SIMD now being enabled, which is ok. I see LTO was not used in the 6.x build though.
bmarkus, could you update libjpeg-turbo in all 6.x with LTO and --without-turbojpeg passed to configure?