I already remapped ATC responses over to numpad a while ago but if I can toggle the window open/closed then I can avoid taking that massive FPS hit from having it on another monitor.
In the longer term it would be neat to use sim-connect to actually transfer the response list to a completely different networked device so I could have the dialogue box open - on another monitor but that monitor is being driven by my 2nd PC.
(I guess there comes a point where sim-connect network stuff gets saturated but…)