Ummm... you are advocating making games slower? Linux is already bad performance wise. The interface idea sounds like it will tell KDE or other window managers that a resolution change is temporary and should save the location of its widgets, so that it can restore them when the change is over. That would take 4 integers per widget, with no performance hit for gaming.
Performance wise this could get a little heavy however it could fix a ton of problems so I say stability first, performance second.