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 14:39:46 +0800
> 
> > > Then run `M-x list-input-methods` and scroll down the screen in input
> > > method panel using the mouse or arrow key will cause Emacs
> > > unresponsive for about 1 minute.
> >
> > It isn't necessarily strange: Emacs looks for the fonts needed to
> > display the relevant characters, so if you have a lot of fonts
> > installed, and some character is not supported, it will take Emacs a
> > lot of time to scan all those fonts.
> 
> Thank you for your analysis. That is really my situation. See below:
> 
> $ 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?  And if you then scroll
down through the HELLO file, do you also see long delays at some
point?