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

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: yantar92@gmail.com,  57207@debbugs.gnu.org
> Date: Thu, 18 Aug 2022 15:50:45 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Can you attach a debugger to this session, and produce a C and Lisp
> > backtrace from Fnarrow_to_region and Fwiden when you do the above?
> 
> Setting a breakpoint on Fnarrow_to_region doesn't trigger -- the buffer
> flips back and forth to [Narrow] anyway.

OK.  Does this buffer have long lines?  What does
long-line-optimizations-p return?