Re: emacs rendering comparisson between emacs23 and emacs26.3

[Eli Zaretskii]

> Date: Wed, 8 Apr 2020 07:02:15 +0000
> Cc: address@hidden, address@hidden, address@hidden,
>   address@hidden, address@hidden
> From: Alan Mackenzie <address@hidden>
> 
> > > Is this not jit-lock-context-time?
> 
> > I have no idea.  But if you are saying that this is "normal", then I
> > disagree: I don't see why the change in fontification after DEL is
> > instantaneous, while the change after typing 'e' takes such annoyingly
> > long time.  Is jit-lock-context-time not involved in the former? if
> > so, why?
> 
> Is the problem more the asymmetry between the deletion and the
> insertion than the actual time taken after the reinsertion?

Not the asymmetry, the slow refontifciation in the latter case.  It
won't help me if both refontifciations were "symmetrically" slow.

> > > However, first setting font-lock-support-mode to nil, then
> > > reinitialising font-lock, deleting then reinserting that "e", the line
> > > after the else _never_ gets its (lack of) face back.
> 
> > So this is still rather a mystery, isn't it?
> 
> It's context fontification.  I'm quite sure of that, now.  To restart
> jit-lock with a new j-l-context-time involves explicitly getting rid of
> a timer and allowing it to restart.

Then perhaps the solution is to reduce the default value of
jit-lock-context-time?