bug#30367: 26.0.91; CC-Mode: Major slowdown when isearching big C++ file.

[Alan Mackenzie]

Hello, Bastian.

That was quick work.  :-)

On Wed, Feb 07, 2018 at 16:27:35 +0100, Bastian Beischer wrote:
> Hello Alan,

> On Wed, Feb 7, 2018 at 4:24 PM, Alan Mackenzie <acm@muc.de> wrote:

> > Hello, Bastian.

> > In article <mailman.8662.1517913372.27995.bug-gnu-emacs@gnu.org> you
> > wrote:

> > > After updating CC-Mode to the latest version in the standalone mercurial
> > > repository I noticed that searching large C++ files has become a lot
> > > slower than before (factor 20 or so).

> > Thanks for taking the trouble to report this bug.

> > How large is large?  Any chance you could supply me with such a sample
> > C++ file that is slow on searching.  Then, in case something else
> > besides the size is slowing it down, I'll have a "working" file to
> > diagnose the bug with.


> Sure, but ​I will send you the file off-list, since I don't want it to
> become public.
> ​

I've got the file you sent me, thanks very much, and I will treat it as
confidential.

Unfortunately, I cannot reproduce the slowdown in that file, at least,
not starting from emacs-26.0.91 -Q.  I think you've got quite a lot of
non-default minor modes active, and I've a suspicion that we're seeing
some interaction between CC Mode and one of these minor modes, or
possibly some other non-default setting you've got set.

Would you please try to reproduce the problem with emacs -Q, and if you
can't, try to pinpoint which one of your settings/minor modes is the one
which CC Mode is working badly with.

We'll crack this!


> ​Cheers
> Bastian

-- 
Alan Mackenzie (Nuremberg, Germany).