Re: emacs rendering comparisson between emacs23 and emacs26.3

[Alan Mackenzie <acm@muc.de>]

Hello!

On Sat, Mar 21, 2020 at 22:19:27 +0000, rrandresf@gmail.com wrote:
> Hi.

> On my TODO list (kind of worn hole). I have several notes.

> One of them is comparing the rendering on emacs23 and emacs26.3. Today
> Alan Mackenzie share an elisp Snippet:

[ .... ]

> When I saw this. The first thing that come to my mind was (it is
> useful on one of the items of my TODO'S). So I did It on xdisp.c from
> emacs26-3 source code.

> Applying it on emacs23 and on emacs26 (on an opi+2e machine with 1 Ghz
> processor)
> This is the result:
> --8<---------------cut here---------------start------------->8---
> emacs-23
> 162.7052059173584
> emacs-26.3
> 281.4721345901489
> --8<---------------cut here---------------end--------------->8---


> The difference is very notorious. I realized it from a long time on
> another ARM machine with 480 Mhz (which i still use aka my phone). But
> I have not got the time and tools for letting you guys know about it. So
> thanks Alan for sharing it.

> Teoretically. What would be the cause of this difference on rendering
> between versions?

There have been lots of bug fixes and new features in CC Mode.  Many of
these have needed extra processing.

Still, an increase of ~75% in processing time over the best part of a
decade isn't that bad.  Surely?  Certainly not when compared with the
increase in available computing power.

One workaround is to reduce the fontification level with
font-lock-maximum-decoration.  A value of 3 is full fontification, 2 is
quite a bit less.

> Best Regards

-- 
Alan Mackenzie (Nuremberg, Germany).