bug#70002: 29.2; GTK3 mouse wheel scrolling

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 25 Mar 2024 19:21:40 +0000
> From:  "Sparapani, Rodney" via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> First I just pick a large file.  Then I try to scroll down.  This works
> with both the LUCID and MOTIF builds that I have made on this system.  
> But with GTK3 there is a big lag where nothing happens. In this case, 
> I counted 13s.  Then there is a scroll.  Here's what view-lossage shows...

The following entry in etc/PROBLEMS could be relevant:

  *** Emacs built with GTK lags in its response to keyboard input.
  This can happen when input methods are used.  It happens because Emacs
  behaves in an unconventional way with respect to GTK input methods: it
  registers to receive keyboard input as unprocessed key events with
  metadata (as opposed to receiving them as text strings).  Most GTK
  programs use the latter approach, so some modern input methods have
  bugs and misbehave when faced with the way Emacs does it.

  A workaround is to set GTK_IM_MODULE=none in the environment, or maybe
  find a different input method without these problems.

Can you try the workaround mentioned above?