bug#4772: 23.1.50; Screen updates very slow

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 :-).

On the plus side, this seems to be the first emacs build in a long time
that actually starts up with the initial frame sized the way I
configured it.


In GNU Emacs 23.1.50.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2009-10-20 on leeloo
Windowing system distributor `RealVNC Ltd', version 11.0.3370
configured using `configure  '--with-x''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Load-path shadows:
None found.