[jsingleton]

I believe that only CNAMEs use the CDN for custom domains (naked domains do not) [0]. So that rules out a chunk but there will be lots of cache misses too. Maybe someone from GH can confirm.

[0] https://help.github.com/articles/about-custom-domains-for-gi...

[michaelmior]

github.io will still also hit the CDN. It's just custom naked domains that will miss.