Graphical Update Slowdown when being Monitored
markj "at" critical.co.uk
Tue Mar 22 13:04:00 2005
Here are some clues :-
1) When switched to raw mode, any desktop resolution, and Poll Desktop
for Changes (rather than VNC hooks), it is much better, and the delay is
almost unnoticeable on the monitored station (the one running VNC
server). The VNC viewer screen updates less accurately, but it is not
too bad, and tolerably keeps up when a lot of screen updates happen, but
not as well as VNC hooks would.
2) Using less colours makes no difference. 8-bit exhibits the same lag
as 32-bit colour.
3) Capturing of alpha blended windows is off on all configurations.
4) VNC is Version 4.1.3 licensed Enterprise Edition on a 100MBits/sec
Windows 2003 Server network.
James Weatherall wrote:
>How much effect VNC Server has on system performance depends heavily upon
>the system hardware & drivers. One things you may wish to try is disabling
>"Capture alpha-blended windows" in the "Capture Method" tab of VNC Server
>Properties. Capturing of alpha blended windows requires use of Windows APIs
>that can impact performance in some cases.
>The VNC Mirror Driver should further improve things, when it is released.
>Wez @ RealVNC Ltd.
>>From: vnc-list-admin "at" realvnc.com
>>[mailto:vnc-list-admin "at" realvnc.com] On Behalf Of Mark Jacobs
>>Sent: 21 March 2005 14:04
>>To: vnc-list "at" realvnc.com
>>Subject: Graphical Update Slowdown when being Monitored
>>We have VNC Enterprise 4.1.3 server installed as a service on some
>>client Win XP Pro SP2 PCs. We use VNCViewer from the supervisor PC to
>>"look at" active screens. We have noticed that when a PC is being
>>viewed, the graphical updates on the viewed PC are slowed down to a
>>point where :-
>>1) The user notices it.
>>2) It interferes with the normal smooth operation of all
>>update the screen.
>>We have even tried a simple text document in Notepad, and
>>and down is smooth when not being monitored, and jerky when being
>>monitored. Any ideas, anyone?