Strange lines appearing on face

Still getting my head around the basics of Blender.

I’m getting these strange lines in two faces

Any ideas?

I’m using Blender version 2.82

I guess you have double faces and the face count is far to high for this scene.
A wireframe screenshot would be easier to help.

Thank you @rigoletto, that has fixed it :slight_smile:

Our Marketing is using blender for shop planning too. I guess you do the same.

Have you checked why you have such a high polycount for the scene. Belonging on your hardware it might be better to go for models that dont use unneeded high polycount. Specially if you plan to bring them to webgl.