Networking :: VNC Server

When I connect to my DSL box from a windows box through the RealVNC server the CPU usage on my DSL box shoots up to 70-90% depending on if I am moving the mouse or not. I'm running a frugal install off of a cf card on 733 MHz, 256 Mb RAM.

Is this common with the RealVNC server?

If not are there any known issues that might cause this that I can correct?

If it is how this VNC server runs does anyone else have any experience with a different VNC server that uses considerably less resources or X11 tunneling through the use of something like Cygwin/X?

original here.