Subject: Re: bug#52298: 29.0.50; Frequent redisplay cycles induced by c-type-finder-timer-func timer in CC Mode

From: Alan Mackenzie <[email-masked]>
Date: Mon, 13 Dec 2021 14:25:20 +0000

Hello, Daniel.

On Mon, Dec 13, 2021 at 00:31:38 +0100, Daniel Martín wrote:
> Alan Mackenzie <[email-masked]> writes:

> > This particular feature simply hasn't worked out well.  If the
> > background scanning were to complete in a few seconds, it wouldn't
> > be too bad.  But nearly two minutes on a modern (well, 4½ yo)
> > machine for just one buffer, with the annoyance of the "stuttering",
> > is not worth the gain.

> If you want another data point, on my 2017 MacBook Pro visiting xdisp.c
> took 1:30 min of background work (using 25% of the CPU).

Thanks, that's helpful.  It confirms that the slow background
fontification check is real, not just an artifact of my current set up.

> Is it possible to make the feature optional, even for the default
> font-lock decoration level in CC mode?  So only the people that want
> more accurate highlighting of types pay the cost of this background
> work.

It would be possible, but I don't think it would be a good idea.  People
generally tend to stay unaware of this sort of option (how many people
know about stealth fontification, for example?), and the cost of
maintaining it is fairly high.

I still think the best thing to do is to rip it out.  It was a
worthwhile experiment, but one which didn't deliver the desired result.

-- 
Alan Mackenzie (Nuremberg, Germany).