Subject: bug#57207: 29.0.50; Fontification is slow after e7b5912b23 (Improvements to long lines handling)

From: Lars Ingebrigtsen <[email-masked]>
Date: Thu, 18 Aug 2022 16:14:54 +0200

Simplified recipe:

(progn
  (pop-to-buffer "foo.txt")
  (flyspell-mode)
  (insert (propertize (make-string 20000 ?x) 'display "foo")
	  "\n\n"))