CPU usage when GUI is on vs GUI is off : Ubuntu 20.04 and Raspberry pi 4

Myself going to use Raspberry pi 4 (8gb ram) with ubuntu 20.04 installed in it, for my projects using ROS. I will use the GUI for some main debugging purposes, or else I would stop the GUI and prefer to communicate via SSH for other uses. What I would like to know is whether stopping the GUI and using only commands (as we do in ubuntu server) will reduce the load in CPU and RAM. I have no clear idea about it, please clarify it and list some factors to be consider to reduce CPU and RAM usage.

Thanks in Advance.