bug#51734: 29.0.50; got slow

[Eli Zaretskii]

> Date: Wed, 10 Nov 2021 09:36:14 +0900
> From: Katsumi Yamaoka <yamaoka@jpl.org>
> 
> I'm sorry for my ambiguous report, but the redisplay or the cursor
> movement on an Emacs screen got awkward and slow recently.  This
> happens on Emacs git master built on 64-bit Cygwin.
> For instance, the cursor moves not smoothly while repeating `C-n's,
> `C-s' takes a couple of seconds for the text searched to appear, etc.
> It should have happened after my build on Thu 4 Nov 22:00 UTC
> through the previous build on Mon 8 Nov 22:00 UTC.

Does this happen with any text in any buffer?  If the problem is
limited to some buffers, please try to figure out which buffers
exhibit the problem.

Also, please show the information collected by report-emacs-bug about
your build details.