Subject: bug#57245: 29.0.50; M-> in a large XML file (without long lines) is slow

From: Dmitry Gutov <[email-masked]>
Date: Tue, 16 Aug 2022 22:32:23 +0300

On 16.08.2022 19:54, Eli Zaretskii wrote:
> Stefan, can you see why syntax-related stuff in sgml-mode is so heavy
> here?

nxml-syntax-propertize might well be heavier than average, but the delay 
scales linearly with the size of the file.

Which seems to be exactly the behavior the "font-lock narrowing" was 
supposed to guard from?