> Date: Tue, 03 Sep 2024 12:27:09 +0100 > From: "Stephane Travostino" <s...@combo.cc> > Cc: 72...@debbugs.gnu.org > > On Mon, 2 Sep 2024, at 13:12, Stephane Travostino wrote: > > On Mon, 2 Sep 2024, at 13:05, Eli Zaretskii wrote: > >>> Date: Mon, 02 Sep 2024 10:18:03 +0100 > >>> From: "Stephane Travostino" <s...@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. > > Update: GTK_IM_MODULE=none does not make it any less laggier. It is mostly > felt in typing and editing source code, and switching to the X11 build makes > it immensely snappier and doesn't feel like I'm working through a remote > connection.
Please try profiling the lagging cases with "M-x profiler", and post the profile here. Po Lu, any other ideas or suggestions? > FYI there are other reports online of people noticing major latency in HiDPI > mode with the PGTK version, especially when the frame is fullscreen (so > there's more pixels to update): > > https://old.reddit.com/r/emacs/comments/ucv0at/awful_performance_with_pgtk_on_wayland/ > > https://old.reddit.com/r/emacs/comments/1acdieh/pgtk_emacs_high_input_lag_at_large_frame_sizes_on/ I don't doubt what you report is real.
