dxpc makes using X over low bandwidth link possible. 

The basic X protocol transfers lots of redundant information.
Client-side, dxpc acts as a proxy X server that handles X requests
over the :8 display, and caches states information that does not
need to be send. It sends the remaining information to the server-side dxpc,
which reconstitutes the full X-protocol for the X server.

ssh can achieve some similar results, with less performance, but also fewer
concerns about security.
