Subject: bug#33670: 26.1; very large c++-mode yank performance regression 25.3_1-x86_64 -> 26.1-x86_64

From: Alan Mackenzie <[email-masked]>
Date: Sun, 9 Dec 2018 12:01:02 +0000

Hello, Chris.

On Sat, Dec 08, 2018 at 13:31:42 -0800, Chris Hecker wrote:
> It wasn’t a string, it was a single line function call.  Very simple code.

> Like:

>    Foo();

Ah.  That's worrying.  The cause of the slowdown will not be found in
that single line of code, rather in its context.

The way CC Mode works is, at each buffer change, a region around the
change where side effects might propagate is calculated.  This region is
then checked for any such side effects.  I'm guessing here, but it might
well be that the region in this case has been extended far more than is
necessary.

Is there any way you could get a copy of the file to me, specifying a
line which shows the problem?  It's practically impossible to debug
otherwise.

Thanks! 

> Chris

-- 
Alan Mackenzie (Nuremberg, Germany).