40W Laser, Artisan and Lightburn very slow movement speed on Material Test

Snapmaker Artisan
1

Hi,

I set up Material Test in lightburn but the movement speed is very slow.
Most time I have to see the that the head is moving very slow in off state between the texts and the squares.
I already tried to set Fast Whitespace Scan to 4800mm/m, but still slow. What I am doing wrong? Using GrBL (No M3) / Gcode.