This is expected. Fractional scaling in Xorg sessions works by rendering
at a higher resolution than your screen(s). So that increases the
likelihood of stuttering compared to integer scaling.
That specific issue will never be fixed because it's a required trade-
off to get fractional scaling working in Xorg. HOWEVER, general
performance will increase a lot in future versions like Ubuntu 20.10 so
that hopefully will be enough to offset and eliminate all the problems
you see.
As for fractional scaling making things slower than not scaling, that is
expected and can't be fixed. If you can then please use Wayland instead.
** Tags added: xrandr-scaling
** Changed in: mutter (Ubuntu)
Status: New => Won't Fix
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https://bugs.launchpad.net/bugs/1890802
Title:
Big performance degradation in X11 + 4K resolution + fractional
scaling in second monitor compared to Wayland
Status in mutter package in Ubuntu:
Won't Fix
Bug description:
Laptop: Lenovo ThinkPad L480
Graphics: Intel UHD Graphics 620 (KBL GT2)
Second monitor: Philips 276E8VJSB/00 4K UHD
There is a big performance degradation in an X11 session + 4K
resolution + 125% fractional scaling in the second monitor compared to
a Wayland session. The mouse cursor moves very slow, dragging Windows
is very slow, scrolling in Firefox is very laggy, so everything
becomes unusable. The performance degradation applies in both displays
even though fractional scaling is only applied in the second 4K
monitor.
Whereas in Wayland, the performance is much better in 4K resolution +
fractional scaling in the second monitor, the mouse cursor and
dragging windows are a lot smoother. I just sometimes notice a slight
jump in the mouse cursor but only in the second monitor, the built-in
monitor behaves normally.
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: mutter 3.36.3-0ubuntu0.20.04.1
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.6
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Aug 7 12:00:26 2020
InstallationDate: Installed on 2020-04-26 (102 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=de_DE.UTF-8
SHELL=/bin/bash
SourcePackage: mutter
UpgradeStatus: No upgrade log present (probably fresh install)
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