A CJK typeface is megabytes because it covers everything. unicode-range-split splits a font into two files: the characters your site actually uses, and everything else, with no glyph dropped. Ordinary pages fetch the small file; the other waits behind a unicode-range until a page uses a character from it. On its own demo, every page fetches 125 KiB instead of 5,632 KiB. Unlike subsetting, a rare kanji in someone's name still renders in your typeface. Free and open source.