I saw somewhere in the forum that this was in the roadmap, but I couldn't find any Feature Request here, so I open a new one.
I know that with the actual protocol, SSL/TLS would put a heavy load (mainly on the server), because of the number of TCP connexions.
Maybe a simple symmetric ciphering with a per host key would be a starting point. (I'm not an expert, but I think it can be implemented quite easily).

Of course, it'd be much better to find a way to use TLS (strong auth, PFS etc...)