bug#20611: 24.4; mutt slow in ansi-term

[Eli Zaretskii <eliz@gnu.org>]

> From: Alexis <flexibeast@gmail.com>
> Cc: mark@hindley.org.uk, 20611@debbugs.gnu.org, mbork@mbork.pl
> Date: Tue, 12 Apr 2016 17:59:17 +1000
> 
> i wasn't sure which version of 23 i should try, so i downloaded 
> both 23.1 and 23.4.

I don't think it matters.

> `configure' for 23.4 required me to call `configure' with the 
> option "--with-crt-dir=/usr/lib/x86_64-linux-gnu". Compilation was 
> then successful. This version showed no lag at all.

So you, too, see a slowdown.

> > Also, were v24.5 and the current master compiled with the same 
> > compilation options, and similar to Emacs 23?
> 
> Not according to the following, no. Having said that, i've not 
> manually made any modifications to the configuration in the 
> tarballs, or on master.

Actually, the options that could affect performance are identical,
AFAICT, thanks.

> > Thanks.  I reviewed all the functions that are high on the 
> > profile (term-goto seems to be the main culprit), and didn't see 
> > any significant changes in them since Emacs 23.  Some of them 
> > were not changed at all.  So I'm puzzled how can Emacs 24 and 
> > Emacs 25 be significantly slower only in term.el.
> 
> Fair enough. One observation, though: the OP and i are both 
> running Debian Jessie.

If in Emacs 24 or 25 you set bidi-display-reordering to nil in the
*ansi-term* buffer, do you see any significant speedup?

Another thing to try is load term.el from Emacs 23 into Emacs 24 or
25, and see if that results in any speedup.

Thanks.