Bug 385276

Summary:	Krita canvas lags on larger displays on macOS
Product:	[Applications] krita	Reporter:	Bernhard Liebl <poke1024>
Component:	General	Assignee:	Krita Bugs <krita-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	alvin, ceryslhancock, halla
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Compiled Sources
OS:	macOS
Latest Commit:		Version Fixed In:

Description Bernhard Liebl 2017-10-01 20:45:30 UTC

Krita's graphics output on macOS is relatively slow, and it is very slow on 5k iMacs.

This seems to be related to QT's QWidget implementation on macOS. And this is probably a well-known problem.

If not, this ticket can keep track of infos about QT's state of things. 

Two useful pointers I found:

https://forum.qt.io/topic/59578/rendering-performance-problems-on-imac-with-retina-5k/24

https://bugreports.qt.io/browse/QTBUG-44228

As QT's OpenGL compositing internally happens with and without Krita's OpenGL canvas, switching to Krita's raster canvas does not make a difference.

Comment 1 Alvin Wong 2017-10-02 04:49:31 UTC

Well, if you apply these patches does it get even slower?

https://phabricator.kde.org/D7973
https://phabricator.kde.org/D7982
https://phabricator.kde.org/D7984

Comment 2 Halla Rempt 2018-02-02 10:54:03 UTC

*** Bug 373676 has been marked as a duplicate of this bug. ***

Comment 3 Halla Rempt 2018-02-06 09:46:08 UTC

Let's just close this as upstream: there isn't anything we can do about it ourselves. For tracking what is being done in Qt, it would be better to use Phabricator.