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

[Ihor Radchenko]

Eli Zaretskii <eliz@gnu.org> writes:

> Ihor, if you set long-line-threshold to a nil value, do the problems
> go away?

Yes.

> If they do, can you put a breakpoint in xdisp.c here:
> ...
>
> and see how frequently this gets called in the same buffer when you do
> whatever shows the performance degradation?

Could you please clarify what exactly do I need to look for? What do you
mean by frequency? Should I share some kind of gdb log?

-- 
Ihor Radchenko,
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