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I have a Mac Pro and a 120 Mbps up (2 Mbps down) broadband cable connection over my Fritbox 7390.

When I use the Microsoft RDP Client or the CorD-Client on OS X (Lion, Snow Leopard, Leopard - all have the same problem), the RDP connection is very slow. When I start Windows in Boot Camp on the same machine and use the RDP client from Windows, everything is fine.

Can anyone tell me the reason for this? How can I fix it? Are there any modifications I can make, such as TCP optimization?

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migrated from stackoverflow.com Aug 5 '11 at 23:29

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The RDS protocol has various optimisations in it, not all of which a client is required to implement. They get added over time. Obviously Microsoft's client implements most of them, the only other client I've seen that implements a lot of them is iTap. But it's commercial (although it was worth it for me, for near to mstsc performance). If you can compile FreeRDP (good luck!), I hear it performs well too. –  ta.speot.is Apr 26 '13 at 21:51

4 Answers 4

I don't know for sure, but I've heard the same complaint. A theory is that on Mac (and Linux) the full images are sent over the network, whereas on Windows some higher level drawing commands are sent, at least for some parts of the screen.

It'd be interesting to try running Remote Desktop Client for Windows on the Mac (or Linux) using Wine, and compare performance this way.

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I had this very issue but the interesting thing is that the RDC to this machine had been working fine some days before – but all of a sudden, over a gigabit network I could see each bitmap block coming across. I tried some other solutions such as executing:

netsh interface tcp set global rss=disabled
netsh interface tcp set global autotuninglevel=disabled

from an elevated commas prompt as suggested here: Vista Remote Desktop Connection Client Slow Delay or Disconnect When Connect to Windows Server 2003 SP2 x64 Edition RDP. That didn't work though.

Then I twigged what had changed since it last worked. I had re-enabled by realtime virus checker (in this case ESET Cybersecurity). I turned off realtime file system protection and instantly RDC and (and also SplashTop desktop, which does the same thing) got back to normal speed.

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Try tweaking the Display settings on the Mac OSX RDP client.

Go to RDC->Preferences->Display, remove some of the "expensive" options in the "while connected" section (such as: show desktop background, show themes, etc...).

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I was having the same issue with both CoRD and Windows RDP. What fixed it for me was adding more memory (I went from 4GB to 8GB).

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