A good assumption is the cutting height and speeds need adjusted to match your setup.
First off have you confirmed that you are definitely cutting at the correct programmed height? Several people has had to adjust it. Incorrect cut height can cause a bad taper. Second I would slow down some more. I would rather have the slag or dross than a bad bevel. I made some changes to my setup once and really had to downshift on 1/2 material. I will see if I can locate the thread I made about it.
To your question changing cutting speed should not require you to change your delay.