I just wanted to report this as a possible bug. The other day after resizing an image and exporting it from Clip Paint Studio as a Tiff file. I wanted to then open the Tiff file in Krita and work on it some more. The file was also about 8000 X 3000 px 300dpi. After trying out some brushes for about 4 minutes Krita crashed. I tried again and the same thing happened. I'm using the latest build of Krita 4.2.4 on Windows 10 with an Ugee 2150 tablet.
I decided to try importing a jpeg instead and had no crash issues- saved it as a Krita file as well just to be on safe side. Worked for around 1.30 hr with no problem.

Can you make a bug report on https://bugs.kde.org?

* Please share the tiff file
* Please provide a crash log: https://docs.krita.org/en/reference_man ... ml#dr-minw
* Please provide the information from help/system information for bug reports

in your bug report.

Also, test saving the opened tiff file as a .kra file, and see whether the crashes go away: if so, this is probably a bug in autosaving this particular tiff file.