I think current hardware is fast enough for it to be useful for certain purposes -- certainly for slow things like checking stats, moving inventory, etc. The window could be small and the frame rate slow to suit whatever the hardware can handle. And hardware is getting faster all the time, so this feature will become more and more useful. As for sending commands, if this is written carefully, I don't think that would be affected.
Edit: I should add that the first guy who asked me for this wanted it because his two PCs were in different rooms of his house but on the same local network. We're not necessarily talking about Internet latencies.
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