Re: I seek QA for CPerl 5.2 (Emacs mode)

[Ilya Zakharevich <nospam-abuse@ilyaz.org>]

[A complimentary Cc of this posting was sent to
Randy W. Sims
<RandyS@thepierianspring.org>], who wrote in article <435556D7.7030303@thepierianspring.org>:

> One wierd problem I find is if I load two copies of a certain file it 
> becomes develishly slow to do anything, even scrolling. This doesn't 
> seem to happen on all files; not sure if it's size or content related yet.
> 
> Eg, If I unpack the Module::Build distribution into two different 
> directories, then load copies of Module/Build/Base.pm from each 
> location, the second buffer becomes slow. The original buffer and any 
> others are not affected. If I close both buffers, then open the same 
> file again, the new buffer is also slow-I must exit emacs and restart 
> before I can work with that particular file because of slowdown.

> This is on Debian (testing) with GNU Emacs 21.4.1.

Confirmed on 21.2.  This effect disappears if I switch to an older
version of font-lock (e.g., one on
  ilyaz.org/software/tmp/font-lock-old.zip
).  One does not need to load the same file or a large file; two files
of size about 80K show the same slowdown in
fontification-by-keywords.  (I used Build.pm and Build/Base.pm.)

Go to the ends of both buffers, then start to scroll back - it is
painfully slow in one of the buffers...

I have no idea how to debug this...  My conjecture is that newer
Font-lock somehow starts to think that it needs to fontify the full
buffer instead of doing only the visible part...

Yours,
Ilya