Emacs 23, so slow to refresh on Windows

[bogossian]

Hi,

with the release of emacs 23.1 last year, I've noticed a huge 
performance
regression with the Windows build. I hoped this would be fixed in the 
next
release, but the version 23.2 is just as slow.
Emacs is especially slow when scrolling through files containing very 
long
lines. With some files, it can hang for several minutes hogging the CPU.

To illustrate the slow down, I built an 8MB file containing a single 
line.
I opened the file in emacs, and then I hit "ESC >" to reach the end of 
the
buffer. I measured the time it takes for emacs to refresh from the 
moment
I typed the macro. Here are the results:

Emacs 21.3.1:    8s
Emacs 22.3.1:   14s
Emacs 23.2.1:   63s

(Test setup: Athlon XP 2GHz, Windows XP SP3)

In the tests above, emacs was started using the command line "emacs -q".
Now, if I repeat the same test using the command "emacs -q -fn 6x13", to
use my usual font, things are getting even worse:

Emacs 21.3.1:    8s
Emacs 22.3.1:   14s
Emacs 23.2.1:  515s

I searched the mailing list and found a guy complaining about similar
problems back in 2008:

http://lists.gnu.org/archive/html/emacs-devel/2008-06/msg01136.html

The replies he received seem to indicate that the performance problem 
was
well known (and related to the new font backend I guess), though it's 
not
very clear whether or not someone was working on addressing it.

So, is there hope to see improvements in the future ?

Regards,

Pierre