gtk slowness?

[<nuke bayside net>]

in case i was ignored last time, or maybe the mail never got to the list..
i was pondering why Gtk is so *slow* compared to say, Qt or Motif? i don't
mean it just has unneeded repaints (although that could use some work
too), things like the popup menus come up very slowly. there isn't any
delay written into the code, but it does take a short moment before a menu
is popped up on a mouse movement (See the Gimp's Filter menu). is there a
specific reason for this? is it anything we can work on/fix?