It just seems like you have too many widgets (windows) for the underlying system.

See Tk::Pane widget size limit? which sound like a similar problem, at least speed-wise.

4.What Else - Use fewer widgets and change their contents based on a scroll bar or something similar as shown in the above referenced post. I.E. instead of building huge Panes where most of it cannot be seen anyway, make a small display and change contents of displayed widgets.