bug#51886: 29.0.50; pixel-scroll-mode garbage collects like crazy

[Eli Zaretskii]

> Date: Tue, 16 Nov 2021 15:21:31 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Starting from `emacs -Q', do M-x pixel-scroll-mode RET, then configure
> it as follows:
> 
>     (setq pixel-dead-time 0)
>     (setq pixel-resolution-fine-flag 1)
>     (setq garbage-collection-messages t)
> 
> Then scroll the display with the mouse wheel.  It will garbage collect
> like crazy, leading to a great deal of stuttering (in emacs-28 as well).
> 
> I want to reuse most of the code in pixel-scroll.el for XInput2 pixel
> scrolling, but this is holding me back, as the excessive garbage
> collection makes it completely unusable.

Did you try to figure out which part of the code produces most of the
garbage?