Subject: Re: bug#15390: 24.3; scrolling in emacs,w32 uses 100% cpu

From: Stefan Kangas <[email-masked]>
Date: Thu, 26 Sep 2019 14:38:53 +0200

tags 15390 wontfix
close 15390
quit

Eli Zaretskii <[email-masked]> writes:

>> The problem is worst when starting at the end of the file and doing
>> page up from there, even after visiting the entire file and starting
>> over at the end, page up starting at the end causes rendering to stop
>> until beginning of file is reached or I stop holding the page up key
>> and wait.
>
> Scrolling back is always more CPU-intensive than scrolling forward,
> due to the peculiarities of the Emacs display engine implementation.
>
> Anyway, I don't see what else I can do with this bug report.
> Scrolling very large windows one line at a time is expensive, but I
> cannot see such a disastrous slowdown on my machine, which is very
> similar to yours.  There's some work in the development code to speed
> up redisplay, maybe it will improve your experience (perhaps try the
> latest development snapshot).
>
> Sorry.

That was 6 years ago and the conclusion was that there is not much we
can do here besides general work that was already undertaken to speed
up redisplay.

I'm consequently closing this as wontfix.  If that's incorrect, please
reopen the bug.

Best regards,
Stefan Kangas