bug#33887: 26.1; Emacs hangs for several seconds when going to the end of an XML file in nXML mode

[Eli Zaretskii]

> From: Fernando Jascovich <fernando.ej@gmail.com>
> Date: Tue, 08 Jan 2019 19:11:02 -0300
> 
> Hi everyone, this is my first email to bug-gnu-emacs, so please let me
> know if I am making some mistake.
> For no special reason, I took this bug in order to start to know  emacs'
> code.
> Following and confirming the details of the bug, I found that indeed the
> performance issue is introduced at commit 0055190174, but not beacuse
> the introduction of `sgml-syntax-propertize-inside`.
> The problem is with the last rule:
> ```
> ("\"" (0 (if (prog1 (zerop (car (syntax-ppss (match-beginning 0))))
>                     (goto-char (match-end 0)))
>                   (string-to-syntax ".")))
> ```
> I can't see the real effect of this rule, I tested xml parsing without
> this rule and it works fine, marking double quotes inside tags as
> expected without this performance issue.
> Do we need to target double quotes outside tags explicitly?

Stefan, any comments?