Thinking about this decision just as a performance one disregards the fact that the code is substantially different. It does seems likely that one way is more intuitive / easier to work with than the other, I wouldn't know which though.
It depends on the probkem younare trying to solve with your GUI, I suppose. Sometimes, it is better to just recreate the whole GUI to adapt to a model change (e.g. the user moved half of the tree nodes somewhere else), sometimes it is easier/faster/... to just update the existing GUI (e.g. update the text of a label inside a complex dialog widget).
