Re: Run `M-x list-input-methods` and then scroll down the screen in input method panel using the mouse or arrow key will cause Emacs unresponsive for about 1 minite.

[Eli Zaretskii]

> From: Hongyi Zhao <hongyi.zhao@gmail.com>
> Date: Sat, 19 Jun 2021 15:16:36 +0800
> Cc: emacs-devel@gnu.org
> 
> > > $ fc-list |wc
> > >   10597   33360 1138340
> >
> > If you invoke Emacs with "emacs -Q" and then type "C-h h", how long
> > does it take Emacs to display the HELLO file?
> 
> It presumably takes the same duration as reported before in this issue.

"Presumably" means that you tried that, and the time it took was
approximately the same?

> Another strange thing: the Emacs installed from apt repo doesn't have
> this problem.

In "emacs -Q" or without the -Q switch?  If the former, what are the
differences between the two Emacs configurations, the slow one and the
fast one?  If the latter, then the reason for the faster operation is
in the init files that you get with the "apt" distribution.