I don't know if this is tied to Krita, but it seems that Krita is not getting GPU acceleration anymore. E.g. Before i could pan / zoom / rotate without any sort of lag, but now its really laggy & my canvas turns black often which it never did before. I tried using Krita 3 - 4.1.1 and the issue persists ( Gpu utilization isn't going above 2 % which led me to belive that the GPU acceleration is turned of). Games work fine both in DX11 and OpenGL. I tried using both settings in Krita for OpenGL & DX11 with a system restart and my canvas still stayed black after i try to rotate. I tried both win 7 and win 10 still same issue. I am currently using win 10 64x with a ryzen 1800x, 16gb RAm, the latest mobo bios and a 970 strix with driver version 399.07 and a wacom cintiq 13hd 6.15 drivers since the newer ones dont seem to work at all. I hope i gave enough information to be helpful :)
Well... If krita used to work before, and now doesn't, something else must have changed on your system. It's a bit hard to try to guess what that could be, but you could try to run Krita as administrator or another user to see whether it's a krita settings issue.
oh, another thing: if the canvas turns black, then that's a sign that the gpu is being used, because it means it cannot handle the texture anymore. The cpu canvas won't show that.
i tried remaking the same document - same canvas size, same layers and it works great no lag at all and proper gpu utilization. The only difference is that i didnt use the rulers (perspektive assistants) in the 2nd document.
Ah, then your GPU probably has a problem with rendering the assistants.
The bug could not be reproduced on my system. Judging from the comments of the reporter and Boud, the issue faced by the reporter is not resulting from a krita bug. Therefore, I am closing this issue.