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

[Po Lu]

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.

Thanks.

In GNU Emacs 29.0.50 (build 74, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, 
cairo version 1.17.4)
 of 2021-11-16 built on trinity
Repository revision: 9bad69e3fa83c0671322011ed4f563c0ff6d4892
Repository branch: feature/xinput2
Windowing system distributor 'The X.Org Foundation', version 11.0.12101002
System Description: Fedora 34 (Workstation Edition)

Configured using:
 'configure --with-xwidgets'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM
XPM XWIDGETS GTK3 ZLIB

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  pixel-scroll-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media rmc puny
dired dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068
epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map
text-property-search seq gv byte-opt bytecomp byte-compile cconv
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils time-date subr-x info cus-start cus-load pixel-scroll
help-mode cl-loaddefs cl-lib iso-transl tooltip eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite emoji-zwj charscript charprop case-table
epa-hook jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice
button loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads xwidget-internal dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 136507 9602)
 (symbols 48 8087 1)
 (strings 32 29616 2128)
 (string-bytes 1 988001)
 (vectors 16 14616)
 (vector-slots 8 197714 10580)
 (floats 8 32 44)
 (intervals 56 20288 5)
 (buffers 992 13))