Re: follow-mode: extremely slow in combination with org-mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Gerald Wildgruber <wildgruber@tu-berlin.de>
> CC: Alan Mackenzie <acm@muc.de>, <emacs-devel@gnu.org>
> Date: Sun, 17 Jun 2018 16:56:00 +0200
> 
> I byte compiled the patched follow.el restarted emacs and began editing.
> 
> It actually seems somewhat faster, though not enormously;

If the speedup is not significant, then I guess there are other
factors at work, although the profile seemed to show I was eliminating
the hottest function calls.

> I will continue working with this patched version to see how it
> goes; I have a more problematic (=slower) machine in my office, and
> I'm am eager to see, if it makes a difference there; at home, where
> I'm testing right now, its a new quad core xeon with 64gb of ram, --
> and it is kind of strange that with such a machine fans start very
> audibly as soon as you start TYPING (not video editing or the like)
> :-)

Each character you insert triggers redisplay, and I'm guessing
follow-mode has many of the redisplay optimizations disabled.  But it
may be interesting to see a profile when all you do is type
self-inserting characters, maybe we will learn something important
from that.

> One more observation: it might be that the slowing down becomes more
> noticeable, the closer point gets to the bottom of the last window
> (lower right edge of my five-fold splitted emacs frame), but I couldn't
> reproduce this consistently.

This could be due to follow-calc-win-start, which loops over windows.
Or maybe there's another loop.  Again, a profile might tell something
interesting.

> Please count on me for any other testing that might be necessary! I'm no
> programmer but will do my best to deliver usable results.
> 
> Here's how the profile looks now, with the patched, uncompiled follow.el
> loaded right before profiling:

Thanks.