Artifact when drawing with large canvases

[Brecht Corbeel]

I am currently draing on a 20.000px x 6.500 px canvas and I get this artifact as seen in the Image I added from a certain stage of drawing I als got this when I was drawing at 12.000 px x 3750. Has been so for a lot of updates nothing ever changes. happens on different pcs aswell.

[Brecht Corbeel]

Other types of artifacts happen aswell I believe ussually when I am at either a large file size or a lot of layers.