Yes, you can tell VNC to hurry up..
Over what kind of network are you using VNC? It could be that your connection is too slow. Same for computers.. If the server doesn't have enough CPU to encode the image, then you have to use less compression.
Turn off Cache encoding
Make sure the CCTV window is the foreground window or tell VNC to poll the full screen.
Use UltraVNC with the Windows video driver.
You can also tell UltraVNC to share only one window instead of the whole screen..