Slow speed over LAN

[KHysiek]

Hello,

I have used before RealVNC over internet to control computers on slow connections (modem, ISDN, ISDN 2 channel). It worked very well, better than I thought on such slow speeds. Now, I wanted to install UltraVNC on LAN ciomputers in my work. But encountered strange problem - it works slow, better than on modem connection but nowhere close to speeds difference (64kbps, about 5000kbps on LAN). When moving, scrolling windows look like about 1-2 fps. This happens no matter what speed I choose in Viewer settings, what compression, and number of colors (works only a bit better, but nowhere close to realtime).
The only real difference was when I have set 16bit desktop color on server computer, but still worked much slower than you could expect on such fast connection (local LAN is 1Gpbs).
I've noticed that CPU utilization on server jumps up to 70-80% when using VNC, but network utilization is just about 2%; file transfer is also very fast, so it's not a problem with network bandwidth. Server(s) are:
P4/2.6GHz, 512MB RAM, ATI 9200,
P4/2.4GHz, 512MB RAM, Intel 900 Graphics (build-in into i865 chipset)
clients tested:
P4/3GHz, 512 RAM, ATI 9600XT,
P4/2GHz, 512MB RAM, nVidia GF3 Ti200.

Tried also RealVNC, works similarly, nothing really better.

[ipsec]

when connecting to these lan clients you can use different viewer compression rates, and I believe this also lessens the CPU utilization..

If you have it set to auto and the network bandwidth is there it goes with the non compressed images ect... try the viewer with multiple options, come up with a good solution for your computers and being able to see what you are remotely controlling..

[KHysiek]

tried that, was misstyped here:

I choose different Viewer settings, type of compression and number of colors (works only a bit better, but nowhere close to realtime).

I've downloaded and installed that external driver and now works noticeably better, however clearly worse that MS Remote Desktop.
Can I set faster "refresh rate" ?

[lizard]

hello
that sounds interesting case to me...

what's your VNC server/viewer version?
what's the screen resolution of the server screen?
how much is the CPU load after applying the video hook driver?
MTU on both of the PCs? the ping time between those?

[netwolf]

I *might* experience kind of the same problem right now: I have a server (running 19.4) that's been online for about 1 week now.
Until yesterday, everything was fine, VNC was fast..., but now the connection is very slow (not always, but almost all the time), everything is delayed (screen updates, actions I perform remotely...).

And unfortunately sending Ctrl-Alt-Del to server does not work, although I'm very sure that I did not disable this feature.
So I can not open task manager and therefore don't know how CPU usage ist.
There are a couple of other processes running on the server, but none of them is supposed to use CPU above normal usage, so I suspect that there is a problem with (or caused by) UltraVNC (mem leak, thread hanging...).

Probably gonna have to restart the entire server soon.
Will report back if I find out anyhing interesting concerning this issue.

[netwolf]

I just noticed that there isn't even an option to disable Ctrl-Alt-Del which I might have set unwillingly, so I guess this is a bug, isn't it ?

Using 19.4 (due to FT-bug of later versions) and XP-SP2 on both sided, no DSM or MS-logon, CAD just doesn't do anything at all...

EDIT: just realised that there is also another way to start task manager (Start - Execute - taskmgr ).
But there's nothing out of the ordinary, mem (and Vmem) and CPU usage are totally normal, it's just the VNC connection which is pretty much lagging.

[ipsec]

EDIT: just realised that there is also another way to start task manager (Start - Execute - taskmgr ).
But there's nothing out of the ordinary, mem (and Vmem) and CPU usage are totally normal, it's just the VNC connection which is pretty much lagging.

and always you can right click on the taskbar and say taskmanager too..