Re: 33% speed up in CC Mode scrolling.

[Alan Mackenzie <acm@muc.de>]

Hello, Martin.

On Mon, Jun 27, 2016 at 08:31:42AM +0200, martin rudalics wrote:
>  > I've just committed b76385c05076f0adaf7cf89d0ed95dfe5e8570e0 to the
>  > master branch.  This takes some code out of CC Mode's font-locking's
>  > hottest loop and puts it back in again in a place where is gets called
>  > less often.

>  > This speeds up CC Mode's scrolling (as measured on our favourite file,
>  > xdisp.c) by about one third.  There may be scope for further optimisation
>  > of this code.

>  > This is a substantial and worthwhile, although not spectacular, speed up
>  > of CC Mode.

> This change has hardly any effect here.  Scrolling xdisp.c with a '-O0
> -g2 -gdwarf-2' build run via emacs -Q is still virtually impossible.

Could you, perhaps, try running with font-lock-maximum-decoration set to
2 for C Mode?  This gives a speed advantage of around a factor of 3 over
decoration level 3, at a cost of some inaccuracies.

I have not finished squeezing cycles out of level 3 font locking.  I can
foresee a total speed up of around 70% (from before the recent 33%).

> martin

-- 
Alan Mackenzie (Nuremberg, Germany).