Rendering regression in Gnus with gnus-treat-from-gravatar

["Adam Sjøgren via \"Emacs development discussions." <emacs-devel@gnu.org>]

A recent change in Emacs has made rendering of articles in Gnus on my
machine noticably slower: uncolored headers flash before the article is
shown in the final rendering.

I have bisected the problem, and this seems to be the cause:

  421eeff243af683bf0b7c6d9181650a1c6900f9b is the first bad commit
  commit 421eeff243af683bf0b7c6d9181650a1c6900f9b
  Author: Philip K <philip@warpmail.net>
  Date:   Tue Mar 17 15:29:53 2020 +0100

      Add support for multiple Gravatar services

      Now supports Libravatar and Unicornify, next to Gravatar (Bug#39965).

      * lisp/image/gravatar.el (gravatar-base-url): Remove constant.
      (gravatar-service-alist): List supported services.
      (gravatar-service): Add user option to specify service, defaults to
      Libravatar.
      (gravatar--service-libravatar): New function, libravatar image host
      resolver implementation.
      (gravatar-build-url): Use alist gravatar-service-alist instead of
      gravatar-base-url.
      * etc/NEWS: Mention new gravatar service option.

   etc/NEWS               |  6 ++++++
   lisp/image/gravatar.el | 43 +++++++++++++++++++++++++++++++++++++++----
   2 files changed, 45 insertions(+), 4 deletions(-)

This makes the option "gnus-treat-from-gravatar 'head" unpleasant. Here
is a video showing the effect:

 · https://koldfront.dk/misc/gnus/avatar-lag.mp4 (4.1 MB)

And here is the "before" video:

 · https://koldfront.dk/misc/gnus/avatar-normal.mp4 (5.5 MB)


  Best regards,

    Adam

--
 "Hur långt man än har kommit                               Adam Sjøgren
  Är det alltid längre kvar"                           asjo@koldfront.dk