Hi Gyrnik, thanks for your reply.
When I use the inkscape-plugin, the laser moves very smoothly and without ever slowing down, but it creates these stripe artifacts.
When i use image2gcode (MPCNC edition) the CNC stops and jerks (around) every few steps, this creates some shaking-artifacts.
I did notice that it helps when I change the jerk and accelaration settings mid-print. But i still have too find the correct settings.
When i lookup youtube videos from mpcnc engravings, most of them just move smoothly without slowing down to burn something.
Would you happen to have a gcode file of which you know works fine on your mpcnc?