bug#4772: 23.1.50; Screen updates very slow

[Jan Djärv]

Tim Van Holder skrev:
> Since yesterday morning's (CET) CVS build (couldn't do one today because
> cvs.savannah.gnu.org currently has no route), I've noticed that screen
> updates are MUCH slower than before. You can clearly see emacs
> repainting things one line at a time. This happens both when
> opening/scrolling files and when emacs needs to repaint part of a window
> because another window was covering it.
> It's not a showstopper as such, but it is having a marked impact on my
> efficiency :-).

Found it.  My fault I'm afarid :-(.  Now fixed.

        Jan D.