Hello everyone!

I had a similar issue, and I found an answer to the slow canvas / slow brush / krita using 99% of the cpu / krita using all the RAM problem.

I have a macbook pro with 16 GB of RAM and I usually never have any issue with performance.
The root of my issue was that I had a layer in my painting that was 200,000x200,000 pixels wide, even if my canvas was around 4000x4000 pixels. By deleting it everything came back to normal.

This super wide layer can be created by zooming out of your canvas and clicking by error outside of your drawing area. The further away you click the bigger the layer become.

Currently the only way I found to find this large layer is to:
- go through each of your layers one by one
- right click "Properties"
- A window open with "Dimension:" at the bottom with a value like "(100,100) (200000,200000)"
- The first parenthesis is the position of your layer, the second is the dimension
- You can now delete this layer or copy the selection you want from it before deleting it

Here is a link to the properties window with the buggy layer: https://ibb.co/rmFN45X

A quick fix to this problem could be to have a warning on the layer if it's x4 time bigger than the canvas.

I hope this post can help someone in the future.
This issue made me go back to photoshop for 2 hours, out of desperation, but krita is just much better so I had to find a solution to my problem.

Thank you Krita team for this awesome software !

Hi ,

I'm just bumping up this topic to see if someone found a solution for it.

stuepitt Any luck?

I'm gonna try dowloading the beta version of Krita 4.3 to see if it helps and report back.

Thanks.

Hey I got krita 4.3 running on my linux laptop and am having similar canvas lag problem. Suspecting it is the same or similar problem.

I am working with a 1000 x 1400 canvas, RGB/Alpha (8-bit integer/channel) sRGB-elle-V2-srgbtrc.icc

The specs on laptop :
Intel(R) Celeron(R) CPU N3060 @ 1.60GHz
Intel Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Integrated Graphics Controller
total RAM : 3.8Gi
screen 1366 x 768 resolution , 40.02 Hz Refresh rate

I have Krita 4.3 running on my other windows laptop which has somewhat higher specs, and krita runs fine.

It seems this forces me to use the windows laptop as painting is unusable this way.


To describe how the lag is:

As others said the brush engine scratch pad shows no lag but there is on canvas. When I start up krita the first thing there tends to be be no
lag, but as I use the brush on canvas soon the cursor and brush stroke starts to slow down and skip. I have increased the memory settings on performance
configuration : memory limit to maximum, internal pool 7%, swap 5%, file size limit 4 Gib. I decreased the fps to 70. Undo stack was above 100 but then I set to 60.
It didnt help.
I only have OpenGL option available for renderer. I've set scaling mode to nearest neighbour. Have tried disabling all these settings including texture buffer.


I've checked each layer for an extra large dimensions, as suggested above, but there were no abnormally large dimensions found.


Have observed there are sometimes small short occasions (eg. after updating settings) where the brush responds without lag, but as the line is drawn the lag increases, as if something is trying and failing to 'catch up'. I have some brush strokes to make with screen blend mode and the lag comes quickly.