"Inkscape 0.48.5.1" is in rapps. It is a GTK+ app.
If we close a menubar icon, e.g. by hovering over another one, ros is horribly slow at redrawing the area where the old expanded menubar was placed beforehand.
2k3sp2_ok.webm has a sane performance in the same VM
This could be the same issue as CORE-15692, but since I am not entirely sure, I will mark it only as "Related" for now, not as "Duplicate"