Re: Display slowness that is painful

[Chong Yidong <cyd@stupidchicken.com>]

"Richard M. Stallman" <rms@gnu.org> writes:

>     This is *really* not the time to make changes in redisplay.
>
> Yes it is.  Even if we had started the pretest already,
> we would fix this bug.  Or what are pretests for?

Managers of successful software projects often make the conscious
choice to postphone resolving bugs whose "fixes" can introduce even
more serious bugs while conferring limited benefits.  (And they seem
to be able to actually make releases...)  If a workaround can be found
that avoids this problem without changing redisplay code, I think it
is preferable.

In this particular case, having looked through the relevant redisplay
code, I don't see any apparent code stupidity going on.  It's simply
the case that, in this file, the first "newline" takes place 340,000
characters in.  The normally negligible delay from displaying glyphs
in octal format (v.s. unibyte-display-via-language-environment) is
magnified by this amount.  The redisplay engine has to scroll through
the entire "line" to check for overlays, text properties, etc., and
this seems to be unavoidable.

Of course, if you can point out a specific redisplay optimization that
we're missing, I'm all ears.