The problem here is the version available into BT4 repository which is 1.1-1.1 (libxcb1, libxcb-xlib0)
This version has bugs noticed when using gnome through xdmcp, here is:
#487635 - Performance...

Just a small comparison NX vs. VNC:
NX is much faster, with a better technologie solution. VNC print screems and send to client. It's heavy and crashs a lot with some processment. NX packages should...

I tried to use nxserver too, but It was really hard to find decent documentation. Dudes from many forums in internet say different ways to configure e solve problems, but I didn't have success too.
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