bug#21597: 25.0.50; Extremely slow redisplay on emacsclient

[Eli Zaretskii <eliz@gnu.org>]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Thu, 1 Oct 2015 10:26:31 -0400
> 
> BUG: All basic operations like navigation (C-p, C-n,..), typing in the
> minibuffer, etc are extremely sluggish.. latency in the order of 10s of
> seconds!
> 
> I am seeing this bug since the emacs built from master yesterday and even in
> the latest build as of writing this email.
> 
> The bug is not seen when running emacs -Q&.
> 
> But it is seen if try to get "emacs -Q" behaviour in emacsclient.
> 
> So I moved my actual init.el to a temp file and add just the below code in the
> init.el
> 
> (require 'server)
> (if (not (server-running-p))
> (server-start))
> 
> - After that, start "emacsclient -a '' -c &". The *scratch* buffer should open
> in a frame. 
> - Now when you do something simple like C-p, you won't see the cursor move at
> all. But as soon as you try to type something, it will get typed on the above
> line, that too with a huge latency between the moment you hit a character and
> that char showing up in the *scratch* buffer.

Very strange.  I don't see anything like that here.  Did you run
emacsclient on the same machine where the Emacs server runs, or over a
network?

> I believe this to have been caused by this commit:
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=5c9304ea86b8cfc9d0b6d7769b90bd56e5dd1313

If you revert the changes in that commit, does the problem go away?
(Please disregard the changes in gdb-mi.el, they are unrelated.)  If
it does, can you try reverting each hunk separately, and tell which
one has the most effect?

Thanks.