Hi,
I have a trouble with brushes bigger than 1000px(tested up to 3k). Changing size of brush above 1000px taking a while. And each stroke has a lag at start (this happening on both mouse and tablet, just 1 sec. lag without straight line), and after lag it is working ok until i start a new stroke. Instant preview gives more performance on drawing, but not solve annoying lag at stroke start.
Tested on Manjaro Linux XFCE, A4 300dpi 8bit rgb canvas, Krita 4.1.5.
PC specs: Intel i5 3470, 8Gb RAM, SSD Drive, GPU HD7770.