Something happened with the frame rate of terminal emulators lately. It looks like there’s a trend to run at a high framerate now? I’m not sure exactly. This can be seen in VTE-based terminals like my xiate or XTerm on Wayland. foot and st, on the other hand, are fine.

My shell prompt and cursor look like this:

$ █

When I keep Enter pressed, I expect to see several lines like so:

$
$
$
$
$
$
$ █

With the affected terminal emulators, the lines actually show up in the following sequence. First, we have the original line:

$ █

Pressing Enter yields this as the next frame:

$
█

And then eventually this:

$
$ █

In other words, you can see the cursor jumping around very quickly, all the time.

Another example: Vim actually shows which key you just pressed in the bottom right corner. Keeping j pressed to scroll through a file means I get to see a j flashing rapidly now.

(I have no idea yet, why exactly XTerm in X11 is fine but flickering in Wayland.)

(#2726vfq) st tries not to redraw immediately after new data arrives:

https://git.suckless.org/st/file/x.c.html#l1984

The exact timings are configurable.

This is the PR that changed the timing in VTE recently (2023):

https://gitlab.gnome.org/GNOME/vte/-/issues/2678

There is a long discussion. It’s not a trivial problem, especially not in the context of GTK and multiple competing terminal widgets. st dodges all these issues (for various reasons).