Re: emacs rendering comparisson between emacs23 and emacs26.3

[Stefan Monnier]

> I think so too.  I responded to that by saying people should not turn on
> this mode for those files:

Performance has to be be good in files without open-parens in column-0.
So setting this var *should* provide no significant performance benefit
(otherwise it means performance is not good enough in files without
open-parens in column-0 and we should fix that).

A setting that is not just a performance heuristic would be fine,
e.g. something that causes the syntax-ppss state to be forcibly reset to
"toplevel" whenever we bump into an open-paren in column 0 (which seems
to be something Martin wants, so that a non-closed comment doesn't leak
past an open-paren in column-0).  But that's a completely separate issue
(beside the superficial connection that they both have to do with parens
in column-0).

But this too long thread is about performance, and when it comes to
performance any heuristic based on open-parens in-column-0 is
a non-starter AFAIC because they only cover a subset of cases and
we need something that covers the other cases as well.
And AFAIK we already have such a "something", so there's no need to
settle for this half-solution, no matter how cheap it may be nor how
attached to it some people might be.


        Stefan