500% speed improvment for remote control softwareOT
Russell McMahon email (remove spam text)
This thread (best read from bottom up) came from the tight-VNC list (an
outgrowth of the original AT&T Virtual Network Computing remote control
software) but it may well be relevant for other remote control software.
Basically it is claimed that TURNING OFF hardware video acceleration on the
controlled PC increases response speed by 500% - not an intuitive result but
believable enough when you think about his explanation.
[vnc-tight-list-adminlists.sourceforge.net] On Behalf Of Greg vnc-tight-list-admin
The reason it speeds things up for VNC is that it goes through the
normal GDI functions to blit stuff to the screen. VNC hooks into this
code to tell which portions of the screen have been updated. When
Windows uses acceleration to draw the desktop, it bypasses this library
and writes directly to the video card.
VNC can still detect these changes by polling the video card RAM for
changes to the screen, but this is slow since it has to go across the
On Fri, 2002-10-04 at 18:53, Ben Serebin wrote:
> Hello Greg and All,
> Why would disabling Hardware Acceleration setting do this?
> what effects will this have on "desktop" use PCs. Will graphics apps
> slower, what is this doing (e.g. caching the v-ram)?
> > I would like to thank whomever at eSVNC put this little tip at the
> > bottom of their web page.I have been using/hacking on VNC for 5
> > and did not know this bit of information so I felt it might be good
> > post it to the mailing list. I am running TightVNC 1.2.6 so this
> > not just apply to eSVNC.
> > From http://perso.wanadoo.fr/samfd/esvnc/
> > TIP: In order to get maximum refresh rate, responsiveness and
> > performances, it is necessary that you completely disable "Hardware
> > Acceleration" on the machines that run WinVNC (server). It can be
> > in "Display Properties" Panel -> "Settings" Tab -> "Advanced..."
> > -> "Troubleshooting" Tab -> "Hardware Acceleration" Tab set to
> > This makes a big difference, especially over LAN connections and
> > with others VNC distributions.
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