bug#23928: 25.0.95; Performance regression observable with smartparens

[Eli Zaretskii]

> From: Aaron Jensen <aaronjensen@gmail.com>
> Date: Sun, 10 Jul 2016 16:53:45 +0000
> Cc: npostavs@users.sourceforge.net, 23928@debbugs.gnu.org
> 
>  Does smartparens really care about this? Why?
> 
> I’d imagine because of things like ruby’s do/end. It wouldn’t want to match 
> DO/Do/etc.

Then setting case-fold-search locally in the buffer (with setq-local
and its ilk) should do the trick.

> By the way, I tested without the bind and smartparens doesn’t even show up on 
> the profile.

Does this mean that the slow operation is also gone when you do that?

> Would it be worth putting a warning in the docs of `let` for this case?

Maybe in the manual.

> Is it only case-fold-search or are there other vars that require per
> buffer updates to rebind?

Any variable which is global by default, but can be local in some
buffers.