I've built another MOSFET board for switching of the DC side to make very fast switching of the power source possible.
I tested it out and realized that the too long ON-times which I thought were caused by the rectifiers capacitor were still there and therefore were caused by the GCODE.
So better GCODE is needed.
I ordered some fittings, which I want to use for building a watercooled electrode mounting bracket. They should arrive by the middle of the next week.