bug#56682: Fix the long lines font locking related slowdowns

[Gerd Möllmann]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Gregory Heytings <gregory@heytings.org> writes:
>
>> Hmmm...  After 350e97d78e, Isearch locks Emacs with
>> toggle-truncate-lines. Recipe:
>>
>> C-x C-f long-line.xml
>> C-x x t
>> C-s </
>>
>> You have to kill Emacs, C-g does not work.
>
> That's kind of funny :-):
>
> (setq isearch-lazy-highlight nil)

I eventually finishes, sort of.  The many '<' in the XML lead to a stop
every few characters for drawing highlights.  Like a train that stops at
every trash can along the tracks.  That's more stops than with
font-lock.