bug#45224: 28.0.50; eww and GIFS (cpu usage shoots through the roof)

[Madhavan Krishnan]

Hello there,

This is on Emacs 28.0.50 (MAIN branch) with "-Q"

Steps to reproduce the bug:

1) M-x eww 2) Insert this url at the prompt.
https://github.com/manateelazycat/emacs-application-framework

as "fix" I was told (setq shr-image-animate nil) would help, but would
defeat the purpose of GIFS

Below you can find the profile report for the cpu.

#+begin_example
- command-execute                                                4514  91%
 - call-interactively                                            4514  91%
  - byte-code                                                    4197  85%
   - read-extended-command                                       4197  85%
    - completing-read                                            4197  85%
     - completing-read-default                                   4197  85%
      - read-from-minibuffer                                     4135  83%
       - timer-event-handler                                     3423  69%
        - apply                                                  3423  69%
         - image-animate-timeout                                 3421  69%
            image-multi-frame-p                                  3420  69%
            time-since                                              1   0%
           #<compiled 0xbc1b6d5890d29>                              1   0%
       - url-http-generic-filter                                   91   1%
        - url-http-content-length-after-change-function                 89   1%
         - url-http-activate-callback                              81   1%
          - apply                                                  81   1%
           - url-queue-callback-function                           81   1%
            - apply                                                81   1%
             + shr-image-fetched                                   81   1%
         - file-size-human-readable-iec                             6   0%
            file-size-human-readable                                3   0%
          apply                                                     2   0%
       - redisplay_internal (C function)                           39   0%
        - funcall                                                  35   0%
         - #<compiled 0x1c38e9a167702bb5>                          35   0%
          + gui-backend-selection-exists-p                         35   0%
        - tool-bar-make-keymap                                      2   0%
         - tool-bar-make-keymap-1                                   2   0%
          - mapcar                                                  2   0%
             #<compiled 0xd4d9e7eb5da225a>                          2   0%
        + #<compiled 0x37cabbbdf65a500>                             2   0%
  - funcall-interactively                                         317   6%
   - execute-extended-command                                     317   6%
    - sit-for                                                     317   6%
     - read-event                                                 174   3%
      - timer-event-handler                                       161   3%
       + apply                                                    161   3%
      - url-http-generic-filter                                     2   0%
       - url-http-content-length-after-change-function                  2   0%
          url-percentage                                            1   0%
      - redisplay_internal (C function)                             1   0%
       + #<compiled 0x37cabbbdf65a500>                              1   0%
     - input-pending-p                                            108   2%
      - timer-event-handler                                       108   2%
       - apply                                                    108   2%
        - image-animate-timeout                                   108   2%
           image-multi-frame-p                                    108   2%
     + redisplay                                                   27   0%
+ timer-event-handler                                             348   7%
+ ...                                                              71   1%
+ redisplay_internal (C function)                                   2   0%
+ url-http-generic-filter                                           1   0%
#+end_example

Regards
-- 
Madhavan Krishnan