2.5W laser, I'm cutting white cardstock, 210GSM at 600 speed.
As I'm doing carve mode = outline (curve,laser) no other settings are relevant.
Also double check your focus is correct, and you definitely have a flat bed.
I cut some white epson photo paper yesterday and had to change the speed to 250.
Different paper will have different speeds.
White paper from the printer (80GSM) i set the speed to 1200.