It has existed for several years and is now thought to be stable and pass . Use of X over SLIP is slow at best, however, some requests can be dealt with quickly enough to make SLIP acceptable - this is application specific. Running X over PPP still requires re-encoding of the protocol and compression to make it truly useable. The industry standard for dial-up X from The Open Group. LBX enhances performance through reduced packet generation by caching commonly used information such as, connection setup, large window properties, font metrics, keymaps etcetera.
Compression also enhances performance.