Hi! So I've finally migrated to Krita 3 found it pretty cool when I tested it on low-res drawings for fun. But recently I got a project for a children's book illustration and trying to draw in a resolution approaching 5000 to 6000 resolutions width / height and above I've noticed that the brushes, even the simplest ones, lag when I try to use them continuously.

Basically what happens is that it draws instantaneously, no doubt, but I take it that it draws a "lower res" version first for instantaneous response then updates the high-res after the stroke is finished. So after the stroke is finished, while the canvas is updating the brush-stroke, my cursor briefly hangs or lags while I'm trying to make the second-stroke. At this point I can't see where I'm drawing due to the brief lag, and by the time I finish drawing, it updates the second stroke automatically — exactly where I don't want it to be. This is a problem particularly when making cross-hatches and stuff.

The reason I know it's an OpenGL problem is because I've been messing around with the settings to figure out how I could fix this. Disabling it under Preferences > Display makes my brush-strokes faster without lag now. But considering OpenGL might actually be an important feature I'm wary about turning it off, so I thought I'd post this here in case of help.

I run Krita on the latest Ubuntu machine, with an AMD CPU and a GTX 750 Ti card.

EDIT: Just found out the biggest problem of having to turn the OpenGL feature off. Now the canvas zooming is laggy. >_>

EDIT AGAIN: That's strange. I turned OpenGL back on and now the problem has completely disappeared...

Hi Tushantin,

The problem you are experiencing is due to an option called Instant Preview being enabled. This feature allows you to make big brush strokes very quickly because it only shows you a low resolution preview of what you are painting while calculating the actual stroke in the background. It makes painting at high resolutions and with big brushes quite fast, however it can also slow down smaller brushes when you are zoomed in.

This feature is dependent on OpenGL. OpenGL is a language that allows us to utilize your graphics card to perform all of the painting, this is a lot quicker than the alternative, which is painting using your processor. By turning OpenGL off you implicitly also turn off Instant Preview, which is why you no longer experienced the lag.

Of course the problem with this is that you now lose a lot of performance because we no longer use the graphics card. You noticed this and turned it back on, however Instant Preview was still disabled from turning it off, which is why the problem has now resolved itself.

If in the future it happens again, there is a checkbox to toggle Instant Preview under the View drop-down at the top of the application.

Hope this helps!

Thanks very much, Nim! That explains a whole lot. Since Instant Preview Mode is easy to access, I'll also keep that in mind when trying to use larger, more complicated brushes.