Running very slowly on Vista

[Brian McGroarty]

I have the RealVNC Personal edition server running on a Vista machine.
When I connect, display updates are painfully slow. It paints the
screen a lateral stripe at a time, taking 3-4 seconds to update the
display, even when the host and client share a gigabit connection.

Oddly, the first screen update is instantaneous, as are some
full-screen changes such as the Windows defender display-dimming popup
dialogs.

Is there something I can do to speed up the display updates?