If "fixing toolkits" is all that is needed, why hasn't anybody done it? How about yourself?
As far as I can tell, everyone who has tried to speed up X over the network has taken a different route. Maybe once you actually look at the toolkit code, it's not that easy---otherwise it would have been done ages ago.
[quote]But yes, you need a fast network with todays bloated desktops.
"Bloated desktop"? Hardly. Try putting up a 10-year old tcl/tk based GUI which allows you to manipulate 2D graphics by live-changing brightness/contrast. Try doing this over a 12Mbps down connection. This is my use case. And it is ridiculously slow---unusable.