From: Jules Colding <colding@venalicium.dk>
To: Eli Zaretskii <eliz@gnu.org>
Cc: help-gnu-emacs@gnu.org
Subject: Re: Why emacs rendering is slow when encountering long lines?
Date: Mon, 21 Oct 2013 16:39:39 +0200 [thread overview]
Message-ID: <407B3DEF-641B-4766-BDCD-A346CC421EEC@venalicium.dk> (raw)
In-Reply-To: <837gd7l44b.fsf@gnu.org>
On Oct 21, 2013, at 5:00 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> Date: Sun, 20 Oct 2013 19:08:51 -0700 (PDT)
>> From: Jiaxin Cao <jiaxin.cao@gmail.com>
>> Injection-Date: Mon, 21 Oct 2013 02:08:52 +0000
>>
>> Let me provide more information about this. To reproduce the scenario, just create a line containing about 450 chars, and copy the line 10000 times.
>
>>
>> Based on the results, I guess the scroll-down is the bottleneck of the scrolling performance.
>
> Your conclusion is wrong. You assume that scroll-down is just that,
> but it isn't. It invokes the display engine to know where to start
> the next/previous screenful. Try to think of an algorithm to
> determine that, when the buffer might have different fonts, and I
> think you will see why.
I have a file here:
https://github.com/colding/MercuryFIX/blob/master/applib/fixio_tests/check_fixio.cpp
which has an extremely long word (one font, all caps) at line 213. As soon as scrolling down comes within 2-3 lines distance, everything stops for a second or two.
Just a datapoint...
--
jules
next prev parent reply other threads:[~2013-10-21 14:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-20 5:00 Why emacs rendering is slow when encountering long lines? Jiaxin Cao
2013-10-20 10:25 ` Jiaxin Cao
2013-10-20 15:38 ` Eli Zaretskii
2013-10-20 15:50 ` Dan Espen
2013-10-20 16:07 ` Eli Zaretskii
2013-10-20 16:09 ` Allan Streib
[not found] ` <mailman.4348.1382285387.10748.help-gnu-emacs@gnu.org>
2013-10-21 2:08 ` Jiaxin Cao
2013-10-21 3:00 ` Eli Zaretskii
2013-10-21 14:39 ` Jules Colding [this message]
2013-10-21 16:36 ` Eli Zaretskii
2013-10-21 16:16 ` Eli Zaretskii
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