From Newsgroup: gnu.emacs.help

On Saturday, April 28, 2018 at 4:05:39 AM UTC-7, Emanuel Berg wrote:

Eli Zaretskii wrote:

People who discover something important
frequently want that to be the first issue
described in <THE DOCUMENT OF YOUR CHOICE>.
Of course, there's only one such issue that
can ever be the first one in any document...

The first question should be "What is Emacs?"

The first answer on debugging should be "-Q" in
order to find out if the problem is with Emacs
or in the user's setup.

People who have problems with Emacs and come
here and ask about it sometimes get a bit
embarrassed when trying -Q to find out the
problem is with them and not with Emacs.
This Q&A in a FAQ could spare some of them this
experience.

But actually I don't think it is anything to be
embarrassed about. Furthermore they might still
need help with their situation. And really, if
all such cases really were Emacs bugs, that'd
be even more embarrassing :)
--
underground experts united
http://user.it.uu.se/~embe8573

Recently I experienced the same problem and it looks like, the root cause for me was:
```
(add-hook 'after-init-hook #'global-display-fill-column-indicator-mode)
```

Somehow when the column indicator is enabled together with relative numbers it causes flickering.

Likely, it is caused by performance optimizations and probably the indicator is being recalculated on every line movement, since display line number mode might adjust the width and it require redrawing of the whole screen.
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From Newsgroup: gnu.emacs.help

On Wednesday, August 24, 2022 at 3:12:11 PM UTC-7, Dmitrii Kuragin wrote:

On Saturday, April 28, 2018 at 4:05:39 AM UTC-7, Emanuel Berg wrote:

Eli Zaretskii wrote:

People who discover something important
frequently want that to be the first issue
described in <THE DOCUMENT OF YOUR CHOICE>.
Of course, there's only one such issue that
can ever be the first one in any document...

The first question should be "What is Emacs?"

The first answer on debugging should be "-Q" in
order to find out if the problem is with Emacs
or in the user's setup.

People who have problems with Emacs and come
here and ask about it sometimes get a bit
embarrassed when trying -Q to find out the
problem is with them and not with Emacs.
This Q&A in a FAQ could spare some of them this
experience.

But actually I don't think it is anything to be
embarrassed about. Furthermore they might still
need help with their situation. And really, if
all such cases really were Emacs bugs, that'd
be even more embarrassing :)
--
underground experts united
http://user.it.uu.se/~embe8573

Recently I experienced the same problem and it looks like, the root cause for me was:
```
(add-hook 'after-init-hook #'global-display-fill-column-indicator-mode)
```

Somehow when the column indicator is enabled together with relative numbers it causes flickering.

Likely, it is caused by performance optimizations and probably the indicator is being recalculated on every line movement, since display line number mode might adjust the width and it require redrawing of the whole screen.

Basically, I have run -Q and executed:
```
(setq-default
display-line-numbers-width 3
display-line-numbers-type 'visual)

(display-fill-column-indicator-mode)
(display-line-numbers-mode)
```

The I have 2 vertical panes: left is large C++ file and the tight one with a scratch buffer.

When I scroll in the large C++ file, emacs is flickering.
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