Re: State of the overlay tree branch?

[Eli Zaretskii <eliz@gnu.org>]

> From: Sebastian Sturm <s.sturm@arkona-technologies.de>
> Date: Mon, 19 Mar 2018 00:20:13 +0100
> 
> for the record, I just switched back to emacs master (no noverlay) and 
> the time reported by (benchmark-run 1000 (line-number-at-pos (point)) 
> increased by a factor of ~40, to 75-80s. At this level, editing is 
> unbearably slow. With the semantic highlighter disabled, the same 
> measurement yields ~2.5s (still painfully slow, but borderline usable), 
> so about the same time reported by the noverlay branch.

You will have to explain why overlays and the semantic highlighter
affect line-counting.  How about presenting a profile produced by
"M-x profiler-report"?

And the timings you measure are 2.5 _milliseconds_ (the benchmark runs
1000 times), right?  If so, I cannot understand why you say that's
borderline usable, because IME such short times are imperceptible by
humans.  I guess some other factor is at work here, so I'd suggest to
describe more details about your use case.

> Since the time taken by line-number-at-pos seems to fluctuate wildly for 
> (to me) unknown reasons, I'll try and see if I can set up a systematic 
> way to collect reliable data.

Yes, please do.  I'm guessing there's some factor here that is
important to consider.