“With the 3018 CNC systems, many I’ve seen have the maximum speed limited in the firmware to a very low number, like 8.3mm / sec.”
“You can fix this by either reducing your speed to the hardware limit, or increasing that limit in the firmware settings.”
"The settings are here: Grbl v1.1 Configuration · gnea/grbl Wiki · GitHub
You can set them in Edit > Machine Settings in LightBurn."