Next step to speed up dlang.org and the library reference is using a CDN. I tried Incapsula to filter my own dlang mirror. It requires minimal setup effort (configuration Incapsula and setting a CNAME record) and acts as a distributed caching layer in front of the real site, i.e. you still upload files to the existing host.

http://dlang.dawg.eu
http://www.incapsula.com