TIP: Greatly increase remote vncserver performance

jsherk · 2010-02-04 16:33:39

I regularly connect to Xfce 4.4.2 (on Centos 5.4) remotely using vncserver, and I always noticed very very slow and sluggish response, especially whenever I closed an application window. For example, when closing Firefox, it would take 30 to 60 seconds for the window to close and the system would be completely unresponsive during that time. It made using Xfce remotely almost unbearable (every click took several seconds before there was a response) and I was looking for other solutions.

I tried the Performance Tip in the Wiki with regards to fonts and it made small improvement, but it was still SLOOOOW!

One thing I did notice though, that whenever I had Firefox opened to google.com (which has a predominantly white background), the responsive times seemed to be noticeably better! So I decided to change my background color to white on the desktop and see what happened!

By changing my background to solid white, all programs (including Firefox) now close within 1 to 2 seconds. And responsiveness to mouse clicks is almost immediate. Yahoo!!!

How To Change Background Color:
Right-click on the desktop and choose Settings then Desktop Settings. Make sure Show Image is UNchecked, and set the Color Style to Solid Color, and then set First Color to white (#FFFFFF).

I have added this tip to the Wiki here (under Performance Tips > Background Color):
http://wiki.xfce.org/tips

It would be interesting to find out how this affects performance when using Xfce locally, if it all! I cannot try this since the server is 1800 miles away from me!

Please post back with any results (good or bad) for both remote connections and local.

Thanks

DMcCunney · 2010-02-04 19:18:26

jsherk wrote:

One thing I did notice though, that whenever I had Firefox opened to google.com (which has a predominantly white background), the responsive times seemed to be noticeably better! So I decided to change my background color to white on the desktop and see what happened!
By changing my background to solid white, all programs (including Firefox) now close within 1 to 2 seconds. And responsiveness to mouse clicks is almost immediate. Yahoo!!!

One option in TightVNC is to disable display of remote wallpaper for just that reason. (Right click on the tray icon for TightVNC and select Properties. It's an option on the General tab.)

VNC removes the need to run an X-Server package like Exceed on your PC. The VNC server process on the Linux box does the work, and holds the image displayed on your screen. But it takes time to update that image across a network, with how much time depending on the bandwidth and latency of the connection. Reducing the amount of data VNC must send to update your client's screen help performance.

I normally use a telnet session to a command line via PuTTY when accessing a *nix box from Windows, but VNC is just the ticket if I need to get to a GUI.
______
Dennis

jsherk · 2010-02-04 20:24:15

I connect with Putty first and create the SSL secure connection, and then use TightVNCviewer and tunnel thru putty to keep the connection secure, since I could not figure out how to implement an SSL connection with vnc alone.

I use TightVNCviewer (which I believe is a slimmed down version of TighVNC) and it does not appear to have the Remove Wallpaper option, but that would certainly make a noticeable difference I am sure, and would eliminate the need to change the background color to white.

The interesting thing is, that I already had the background color set to a solid color (blue) with no image, but I guess the color blue that I had chosen took up A LOT more time to render and transmit than plain white!

herd · 2010-02-06 11:45:16

I have no setup ready to test it, but I may have a theory to explain this.
Probably, vnc is optimized to cache the root window, the one you adress with xsetroot.

Unfortunately, xfdesktop does not use the real root window for some arcane reasons:
The desktop window is actually another full screen window. This can be seen easily that
conky etc. must have special workarounds to work with xfdesktop or just by xwininfo
giving a nonzero window id when clicking on desktop.

I'd suggest you try to kill xfdesktop alltogether, set your wallpaper with xsetroot, measure the
difference and if there is one:
a) bug the vnc folks until they implement xfdesktop workarounds or
b) bug the xfdesktop developer to take ownership of the root window asap.

wkr,

herd

jsherk · 2010-02-06 12:49:08

I am pretty new to Linux, so I might not be the person to try and test this because I have no idea how to do either of those things (kill xfdesktop and set wallpaper with xsetroot I mean)! :?

sdsdrillbits · 2010-02-10 07:25:09

I am having this kind of problem lately too. Thanks for your advices.

jsherk · 2010-02-10 12:26:35

sdsdrillbits ... did it actually help and make any difference? Can you connect faster now?

panca · 2019-01-05 23:46:07

jsherk, it's a bit late ( wink ), but you made a big difference for me. Ubuntu Studio with XFCE desktop, almost no lag now on cursor movement left, after switching from background image to solid color. There must be some terrible design flaw in XFCE to have the existence of a desktop image have such influence on lag in vnc-performance...

Skaperen · 2019-01-08 01:16:46

it makes sense that a solid color is faster to draw with many fewer bytes of instructions, just like compressed images. there are some design flaws in the original design of VNC. these things have been improved on more recently than when this thread was started. even if the base protocol were to draw 10000 pixels of white by transmitting 30000 bytes of 0xFF, compression could readily compress that better than some complex image.

we also need to be sure we transmit VNC securely. we can easily do this with SSL/TLS, SSH, IPsec, or many other means.

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#1 2010-02-04 16:33:39

TIP: Greatly increase remote vncserver performance

#2 2010-02-04 19:18:26

Re: TIP: Greatly increase remote vncserver performance

#3 2010-02-04 20:24:15

Re: TIP: Greatly increase remote vncserver performance

#4 2010-02-06 11:45:16

Re: TIP: Greatly increase remote vncserver performance

#5 2010-02-06 12:49:08

Re: TIP: Greatly increase remote vncserver performance

#6 2010-02-10 07:25:09

Re: TIP: Greatly increase remote vncserver performance

#7 2010-02-10 12:26:35

Re: TIP: Greatly increase remote vncserver performance

#8 2019-01-05 23:46:07

Re: TIP: Greatly increase remote vncserver performance

#9 2019-01-08 01:16:46

Re: TIP: Greatly increase remote vncserver performance

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