Still, it's nice to know how to do this on Macs.
On Linux the VNC is an X client so one can have multiple instances running each exposing with their own graphical shell.
Does Windows RDP do that ? (I don't know).
TightVNC works the best with low speed networks, it uses JPEG encoding too.
BTW. is is also against the Windows EULA to use VNC server on it !
Still, it's nice to know how to do this on Macs.