GNU bug report logs - #74813
31.0.50; scroll-down is 10x slower and laggy than scroll-up

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Package: emacs;

Reported by: Eval Exec <execvy <at> gmail.com>

Date: Thu, 12 Dec 2024 08:01:01 UTC

Severity: normal

Tags: moreinfo

Found in version 31.0.50

Done: Eli Zaretskii <eliz <at> gnu.org>

Bug is archived. No further changes may be made.

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Message #25 received at 74813 <at> debbugs.gnu.org (full text, mbox):

From: execvy <at> gmail.com
To: Eval Exec <execvy <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>,
 74813 <at> debbugs.gnu.org
Subject: Re: bug#74813: 31.0.50; scroll-down is 10x slower and laggy than
 scroll-up
Date: Fri, 10 Jan 2025 15:30:34 +0800
I try to reproduce on `emacs -Q` for this file: https://raw.githubusercontent.com/bitcoin/bitcoin/refs/heads/master/src/secp256k1/src/precomputed_ecmult.c

It's fundamental-mode, then I notice `C-v` and `M-v` 's scroll-up and scroll-down have performance difference: C-v is more smoother than scroll-up. 



On 1/5/25 11:05 AM, Eval Exec <execvy <at> gmail.com> wrote:
> I have a fever. I'll try again in three or four days.
> 
> 
> On Sat, Jan 4, 2025, 20:05 Eli Zaretskii <eliz <at> gnu.org 
> <mailto:eliz <at> gnu.org>> wrote:
> 
>      > From: Eval Exec <execvy <at> gmail.com <mailto:execvy <at> gmail.com>>
>      > Date: Sat, 28 Dec 2024 21:31:28 +0800
>      > Cc: 74813 <at> debbugs.gnu.org <mailto:74813 <at> debbugs.gnu.org>
>      >
>      > Friendly Pong. I'm busy these days. I will upload a reproducible
>      > minimal init.el tomorrow.
> 
>     Did you have time to come up with a reproducible recipe?
> 
>      >
>      > On Sat, Dec 28, 2024 at 6:59 PM Eli Zaretskii <eliz <at> gnu.org
>     <mailto:eliz <at> gnu.org>> wrote:
>      > >
>      > > > Cc: 74813 <at> debbugs.gnu.org <mailto:74813 <at> debbugs.gnu.org>
>      > > > Date: Thu, 12 Dec 2024 11:11:45 +0200
>      > > > From: Eli Zaretskii <eliz <at> gnu.org <mailto:eliz <at> gnu.org>>
>      > > >
>      > > > > From: Eval Exec <execvy <at> gmail.com <mailto:execvy <at> gmail.com>>
>      > > > > Date: Thu, 12 Dec 2024 15:59:51 +0800
>      > > > >
>      > > > >
>      > > > > I opened a large rust file, about 5000 lines.
>      > > > > scroll-up is quick and smooth, no laggy:
>      > > > > [...]
>      > > > >
>      > > > > but scroll down is very laggy:
>      > > > >
>      > > > >         2667  87% - command-execute
>      > > > >         2666  87%  - funcall-interactively
>      > > > >         2666  87%   - evil-scroll-page-up
>      > > > >         2666  87%    - scroll-down
>      > > > >         2665  87%     - apply
>      > > > >         2664  87%      - ad-Advice-scroll-down
>      > > >                            ^^^^^^^^^^^^^^^^^^^^^
>      > > > >         2663  87%       - #<primitive-function scroll-down>
>      > > >
>      > > > First, you have an advice on scroll-down.
>      > > >
>      > > > Furthermore, scrolling down exposes portions of a file that
>     were never
>      > > > seen before, which needs to fontify them.  If fontification is
>      > > > expensive, it is expected that you will see some lags.  What
>     happens
>      > > > if you scroll down, then go back to the beginning, and then
>     scroll
>      > > > down again -- is scrolling down the second time much faster?
>      > > >
>      > > > Also, you didn't say which major mode did you use for this file.
>      > >
>      > > Ping!  Can you please answer my questions?
>      >
> 
> 




This bug report was last modified 171 days ago.

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