VNC speed and compression

Simon Byles simon "at"
Thu, 23 Jul 1998 15:54:58 +0000

James [Wez] Weatherall [mailto:jnw "at"] wrote on Thursday, July
23, 1998 2:50 PM:
> I would tend to agree with this.  If WinVNC is sluggish on a 
> P200 machine
> then this suggests that either WinVNC has been misconfigured or that
> something else in the system is taking up most of the 
> available CPU time
> and leaving too little for WinVNC to use. One obvious possibility is
> that the Poll Full Screen option has been enabled by mistake 
> for WinVNC,
> which will cause a serious performance hit.

This reminds me, I was a bit confused over the meaning and difference
between these polling options. Is the general idea to have none on if
you can and switch on an option or two if you need them? 

I'm running VNC server on an NT Server box (P200Pro) and Viewer on a
P133 Win95 box across standard Ethernet (no switching). I did have Poll
Window Under Cursor on and I put the sluggishness down to the busy
network. But seeing this thread prompted me to look at the Task Manager
and there I saw VNC's processor usage at 17-21% idle and 65% when I
moved the mouse, 80%+ when I dragged a window about. So I switched off
the polling and it now idles at 1%, going to only 21% dragging. The
display updates slower (it "pauses") but I can live with that.

But do I need any of the polling on? Perhaps Poll Console Windows? Is
there a known best compromise in this situation or do I just suck it and

Thanks for your continuing advice to us all,


Simon Byles 
IT Co-ordinator / Publications Officer 
The Institute of Mathematics and its Applications 
Telephone 01702 354020 

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