So what you are saying is that it is a continuous path run that will default to the speed set as max x instead of you "pulsing" each pixel as individual lines of code. I suppose that would make the gcode file way huge. I don't think hardcoding a max X speed in the firmware is something that should be done for keeping a solid laser run reduced. I do believe there is a MAX X gcode that can be sent as a starting code parameter.
Would you be willing to modify the code to the see the intensity above a certain number (in this case S198) and force a F code for speed to be at least the Feedrate? Then I can adjust the max feedrate for the code easily?