Bug 349436

Summary:	the brush lags if I try to draw fast or with very long strokes
Product:	[Applications] krita	Reporter:	Kai <kaisoulchan>
Component:	Brush engines	Assignee:	Krita Bugs <krita-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	darko.baruh, dimula73, halla, portnov, skayrunesh, welcome
Priority:	NOR
Version First Reported In:	2.9.1
Target Milestone:	---
Platform:	unspecified
OS:	All
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Kai 2015-06-21 02:55:33 UTC

While drawing long/fast strokes with any brush, it lags horribly to the point it takes a full minute to respond completely and i could be on a whole different stroke by then. 

Reproducible: Always

Steps to Reproduce:
1. choose any brush
2.make a fas/ long stroke in any direction
3.wait for the brush stroke to catch up to you

Actual Results:  
The stroke would be slowly going across the page at a very slow rater whether you're still on this stroke or another.

Expected Results:  
it should have been fast and instant, not taking 30 seconds for one brush stroke to complete!

Comment 1 Ilya V. Portnov 2015-06-21 12:05:20 UTC

Please provide more information:
* What size of image are you creating? 1000x1000 or 10k x 10k ?
* What kind of brush are you using?
* Is OpenGL turned on in settings?
* What OS are you using?
* What kind of videocard are you using? With which drivers (free or proprietary, in case of Linux)?

With those images I tried, does not reproduce for me neither on Kubuntu with build from PPA nor on Debian with build from git.

Comment 2 Ilya V. Portnov 2015-06-21 12:14:10 UTC

With some brushes, if i draw long lines fast, the brush lag can be about 1-2 seconds. But not 30 seconds and not for every brush.

Comment 3 Halla Rempt 2015-06-21 12:55:41 UTC

Also -- please update Krita to a more recent version!

Comment 4 Dmitry Kazakov 2015-06-21 13:07:25 UTC

Hi, Kai!

Could you generate a performance report as described here?
https://community.kde.org/Krita/Docs/Bug_Writing_Guidelines#Painting_performance_bug

And, if possible, could you make a video of what you are doing and how slow it is?

Comment 5 Camille Bissuel 2015-06-23 13:50:27 UTC

Can reproduce with any textured brush with a 8K canvas and a brush size superior to 200 or 300 px... especially with a 1000 px size. 
I insist on the "textured".

But not so surprising ;)

OpenGL turned On,  ATI Radon open source driver on linux.

Comment 6 Darko 2015-07-11 12:20:41 UTC

I have the same problems on 2.9.6 Using Linux mint Cinnamon 17.2 and wacom intuos 5.
Didn't have this problems on 2.9.5. I tried to raise the performance bars but didn't helped.
I have short video of the problem.
https://vid.me/XJmD
P.S. On all brushes that I tried in the video the brush stabiliser was no smoothing.

Comment 7 Ilya V. Portnov 2015-07-11 14:44:25 UTC

I saw similar lags with some brushes, when I accidentally turned on debug output for krita. With debug turned on, it outputs tons of debug info to stdout, and that output takes more time than actual drawing. Please run "kdebugdialog" and make sure that all checkboxes against everything started with "krita" are disabled.

Comment 8 Darko 2015-07-11 16:12:33 UTC

All the checkboxes started with "krita" in "kdebugdialog" were already disabled. So no problem there.

Comment 9 Camille Bissuel 2015-07-15 07:55:36 UTC

@Darko What is your videocard and driver ?

Comment 10 Halla Rempt 2016-06-16 09:45:10 UTC

Closing, since we're now at 3.0 (which has other performance issues, but those are already tracked in other bug reports and have other causes, so this isn't a duplicate)