Dolphin and file cache-mirrors.

I think Dolphin have to offer ability for caching files with reverse proxy servers (squid, nginx, apache,... ).
Using a reverse proxy with cache gives:
- less traffic (if proxy-server is located in another place of main server);
- takes a part of load of main server;
- increase file downloading speed (proxy-server responses faster than web-server);
- ability to share files to demilitarized zones.

For this it needs to add site config element $site['files_url'] which by default is same as $site['url']. But who wants to use proxy caching can change this config element as he wants.

I find a lot of documents how to configure squid as reverse proxy by google.