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Browsing inside Remote Desktop session

Hi,

I am running some 2008 terminal servers in VMware ESXi 5.1. They are meant for about 25 users each to use a few specific applications and access some folders. They do everything they are supposed to do.

Some users insist on using firefox inside this RDP session. That works fine, too. If the user however, opens a page with moving flash content, mouse-over-effects or just large images, if he scrolls this page all over his 24" screen, then performance is very slow, as is to be expected.
Also, scrolling through PDF files ore word files with embedded images cause this issue.

I have done some testing and even though I know this is not a very good idea, I have tried to find out why. The lines have plenty open bandwith on both ends. CPU and RAM look good.
What exactly is the bottleneck in this constellation? Is there anything I can do to help this issue to function a little better at least?

Thanks,
Ralph

serialband

Normally, only a small portion of the screen actually changes in a RDP session when you're not scrolling or refreshing the screen. The screen is cached on your client so you don't have to keep updating everything. They probably pass API calls to draw identical fonts or window elements to keep things "fast". When an image appears, or moves, the entire canvas needs to be redrawn and that pixel data also needs to be transferred along with the API calls for the section. Those mouse over effects in firefox are not Windows elements, so they're full pixels that need to be transfered as the effects are drawn as it "pulls down". It doesn't just draw the changed pixels like they do with MPEG.

If you want it to run faster, force the color depth setting from Millions (24 bit) to Thousands (16 bit), since most people can't tell the difference easily. Most older LCD monitors didn't display millions of colors either. You can test your monitor here http://www.displaycalibration.com/color_depth.html

Uninstall flash from the VMs. It will keep your users off Firefox in RDP. Don't give them an excuse to run videos in RDP.

Ralph Scharping

ASKER

Hi serialbrand,

RDP color depth is already reduced to 16 bit on the server side - I think this is even default.
How much does the performance of the RDP Client device effect the overall performance? Is there any optimisation that can be done? Where does the slowdown occur? If network, CPU, RAM and internet line all have free resources, where is it lagging?

Flash is an idea. But that does not improve PDF-scrolling issues...

Thanks,
Ralph

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serialband

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Ralph Scharping

ASKER

Thanks - if there is nothing I can do, I can probably drop it here.
It's just that I wondered where EXACTLY the lagging comes from. If there is unused bandwidth on the network, CPU, RAM and everything else is operating way below the limit where is the limiting factor? I am aware that RDP is not meant for multimedia usage. Still I'd like to know what makes it lag.

Inside our LAN performance is fine even when scrolling PDFs with large pictures. I can stack a bunch of routers behind each other, make the traffic pass through 20 hops, make the ping travel for 25-40ms, and it's still fine. As soon as it passes out through the WAN, it's no longer fine. Why?
But you are right, maybe I should concentrate on more worthwhile things...