Re: emacs rendering comparisson between emacs23 and emacs26.3

[Stefan Monnier]

> --8<---------------cut here---------------start------------->8---
> emacs-23
> 162.7052059173584
> emacs-26.3
> 281.4721345901489
> --8<---------------cut here---------------end--------------->8---
[...]
> Teoretically. What would be the cause of this difference on rendering
> between versions?

It's hard to tell without digging deeper, it could be in part due to
changes to the actual redisplay code or to the rest of the C code, but
I suspect it's mostly due to improvements (featurewise) in CC-mode.

I just compared this test's performance using `c-mode` vs using
`sm-c-mode` (a comparatively very bare-bones major mode limited to
"normal" C (no support for any C++ feature nor for old K&R-style C, nor
for very modern C)), and the speed difference was even larger.


        Stefan