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#72960
31.0.50; PGTK Wayland exhibits more lag than X11 version
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On Mon, 2 Sep 2024, at 13:05, Eli Zaretskii wrote:
>> Date: Mon, 02 Sep 2024 10:18:03 +0100
>> From: "Stephane Travostino" <sph <at> combo.cc>
>>
>> Heavy operations, such as scrolling back and forth in a buffer, are
>> noticeably laggier, for lack of better word, in the PGTK/Wayland version
>> than the X11, both tested on KDE in Wayland mode.
>>
>> Affects both 29.2 and the latest HEAD compiled a few days ago.
>>
>> I am unsure whether it is a KDE or Emacs problem.
>>
>> Running on an AMD RX 6800 XT graphics card on a HiDPI 4k screen at 2x
>> scaling.
>
> AFAIU, this is a problem with GTK input methods. From PROBLEMS:
>
> *** Emacs built with GTK lags in its response to keyboard input.
> This can happen when input methods are used. It happens because Emacs
> behaves in an unconventional way with respect to GTK input methods: it
> registers to receive keyboard input as unprocessed key events with
> metadata (as opposed to receiving them as text strings). Most GTK
> programs use the latter approach, so some modern input methods have
> bugs and misbehave when faced with the way Emacs does it.
>
> A workaround is to set GTK_IM_MODULE=none in the environment, or maybe
> find a different input method without these problems.
Thank you, though without more scientific methods of measuring latency I can't tell if that helps or not.
I noticed I had pixel precision scrolling mode on and that contributed a large part to that feeling of lag compared to other programs. If Firefox is able to smooth scroll at 60 Hz, I would say empirically Emacs PGTK would scroll at 15 Hz, making navigation in the buffer a choppy affair.
This bug report was last modified 287 days ago.
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