HTTP compression: http://en.wikipedia.org/wiki/HTTP_compression
I know it's used: Server > Client but is that it could be used in the direction Client > Server ?
With this kind of thing we would lose in latency, but we could use a lot more thread. I do not know if the server accepts this type of query ...
EDIT: "Compression as defined in RFC 26 can be applied to the response data from the server (but not to the request data from the client)"