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As mentioned, when I do X11 forwarding using basic ssh -X username@hostname it's quite sluggish. But interestingly, when I use nxclient, it's significantly faster.

I'd rather use ssh instead of nxclient, due to various reasons.

I've tried turning on compression and setting ciphers, (i.e. ssh -X -C -c blowfish-cbc,arcfour username@hostname) but it's still pretty sluggish.

Why is that? How do I speed up ssh X11 forwarding to be up to par with nxclient?

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The whole point of nx is to speed things up.... – demure Jun 5 '13 at 16:30
@demure Are you saying there's no way basic ssh -X could be up to par with nxclient? – oaskamay Jun 5 '13 at 18:34
up vote 4 down vote accepted

The NoMachine NX library is basically a derivative of DXPC. It is stated in wikipedia "The NX scheme was derived from that of DXPC – the Differential X Protocol Compressor project".

So while ssh -C -X simply compresses whatever you feed it with (in your case, an X session), NX goes the extra mile to NOT send the 'unchanged' bits of information that it has already sent, thus the 'differential' term. Once what needs to be sent has been decided, nx will actually use ssh (or rather an nx derivative of ssh, nxssh to transmit session information).

So there is no way that the ssh -X -C will be as efficient as setting up an nx session. (nxclient is only one end of the deal btw, you will need the corresponding nxserver - i.e you cannot just replace the nxclient with ssh -X).

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