font file output is not optimized
A simple test like follow:
1. get http://www.apple.com/wss/fonts/PingHei/v1/PingHei-light.woff (size 992 KB)
2. convert into ttf via https://andrewsun.com/projects/woffjs/woffer-woff-font-converter/ (size 2.2 MB)
3. `fontmin pinghei.ttf > output.ttf` (size 8.4 MB)
4. `fontmin pinghei.ttf -d > output.woff` (size 7.5 MB)

Using my [character-map](https://github.com/bitinn/character-map) command to check `output.ttf`, it contains the same glyphs as the `pinghei.ttf`, so somewhere in between it picks up a lot of fat.
