[vim/vim] #18002 wayland gtk redraw slow on `:version` and `:highlight` (PR #19062)

dezza

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Jan 2, 2026, 7:44:28 AMJan 2

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Since patch 9.1.1585: Wayland: gvim still needs GVIM_ENABLE_WAYLAND,
the message window has been slow at drawing especially :version and
:highlight.

Since wayland redraws entire screen between updates (contrary to X11),
there are most likely- many more gains in perf in other paths not
discovered.

The issue is easily reproduced on;
Fullscreen, fractionally scaled, HiDPI displays (4K)

You can view, comment on, or merge this pull request online at:

https://github.com/vim/vim/pull/19062

Commit Summary

5f788cb refactor: gui.is_wayland for checking display
907f675 perf: gtk-wayland slow redraw

File Changes

(4 files)

Patch Links:

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dezza

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Jan 2, 2026, 7:55:12 AMJan 2

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@dezza pushed 1 commit.

bddabb3 fix: ifdef

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Christian Brabandt

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Jan 2, 2026, 8:16:05 AMJan 2

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@chrisbra commented on this pull request.

In src/gui.c:

> @@ -9,6 +9,9 @@
  */
 
 #include "vim.h"
+#if defined(FEAT_GUI_X11) && GTK_CHECK_VERSION(3,0,0)

I think this should be:
#if defined(FEAT_GUI_X11) && defined(GDK_WINDOWING_WAYLAND) && GTK_CHECK_VERSION(3,0,0)

according to https://docs.gtk.org/gdk4/wayland.html

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dezza

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Jan 2, 2026, 8:31:35 AMJan 2

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@dezza commented on this pull request.

In src/gui.c:

> @@ -9,6 +9,9 @@
  */
 
 #include "vim.h"
+#if defined(FEAT_GUI_X11) && GTK_CHECK_VERSION(3,0,0)

You linked the gdk4 docs, I will look into it, thanks.

Made PR into a draft, see the tests failing and now it seems its back to slow for me since editing it.

Will continue trying- I was sure I had it.

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dezza

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Jan 7, 2026, 10:42:21 PMJan 7

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@dezza pushed 2 commits.

4d641f7 refactor: gui.is_wayland for checking display
ba6fef5 perf(wayland): skip compositing, use direct blit

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dezza

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Jan 8, 2026, 5:34:22 AMJan 8

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@dezza pushed 1 commit.

977270e lint: vim codestyle brace after paren

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dezza

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Jan 8, 2026, 3:13:15 PMJan 8

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@dezza pushed 1 commit.

2e822fd fix: scroll-up was buggy and repeated same lines down- need clip, save, restore

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dezza

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Jan 23, 2026, 3:35:04 AMJan 23

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@dezza pushed 4 commits.

cab909c refactor: gui.is_wayland for checking display
719dd78 perf(gtk-wayland): avoid early redraws; compositor does redraw
ec87708 perf(gtk-wayland): avoid reallocs, optimize scroll copy
3434019 perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 4:18:20 AMJan 23

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@dezza pushed 2 commits.

3673452 perf(gtk-wayland): avoid reallocs, optimize scroll copy
3ed531a perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 4:21:07 AMJan 23

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@dezza pushed 2 commits.

21f245a perf(gtk-wayland): avoid reallocs, optimize scroll copy
5a41d82 perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 4:36:57 AMJan 23

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@dezza pushed 2 commits.

d71f5a2 perf(gtk-wayland): avoid reallocs, optimize scroll copy
a691f41 perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 4:52:25 AMJan 23

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@dezza pushed 4 commits.

8baecba refactor: gui.is_wayland for checking display
4e7f06e perf(gtk-wayland): avoid early redraws; compositor does redraw
c0e0710 perf(gtk-wayland): avoid reallocs, optimize scroll copy
8f9a305 perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 6:09:04 AMJan 23

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@dezza pushed 4 commits.

7821040 refactor: gui.is_wayland for checking display
2ee8f2c perf(gtk-wayland): avoid early redraws; compositor does redraw
0c3cab4 perf(gtk-wayland): avoid reallocs, optimize scroll copy
c69b160 perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 7:08:50 AMJan 23

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@dezza pushed 4 commits.

68528ad refactor: gui.is_wayland for checking display
b542ec0 perf(gtk-wayland): avoid early redraws; compositor does redraw
9c2ddbf perf(gtk-wayland): avoid reallocs, optimize scroll copy
55e824c perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 7:21:10 AMJan 23

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@dezza pushed 2 commits.

c97633d perf(gtk-wayland): avoid reallocs, optimize scroll copy
80db39b perf(gtk-wayland): don't block input loop

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dezza

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Jan 23, 2026, 1:02:40 PMJan 23

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@dezza pushed 2 commits.

0d1ac2a perf(gtk-wayland): avoid reallocs, optimize scroll copy
5501108 perf(gtk-wayland): don't block input loop

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dezza

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1:08 PM (5 hours ago) 1:08 PM

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dezza left a comment (vim/vim#19062)

@chrisbra hey chris, congrats on the new release, thanks for your continued valued effort and cheers to bram!

Did you see the new changes here?

Its a shame gvim is so slow, almost unusable imo. The "black" partial redraws mentioned and the slow scrolling as well as messagewin redraws.

My CPU was in for warranty just got a replacement, but will be installed shortly.

Reducing import guards in this PR definetily could happen, maybe just check gui.is_wayland and let that default to false when GDK_WINDOWING_WAYLAND false.

Regarding the vim_input_buf - how important is that for GUI? I understand X11 had reasons to trigger the g_main_context_iteration, but for wayland this seems to be different. I have not encountered missed key input at any point with that, but is there a case where it is critical? feedkeys?
Coverage tests ?