another thing to note… klipper firmware takes the heavy processing typically handled by the printer control board, and offloads the burden onto the computer or device you have hooked up to the printer, processing and feeding the gcode one line at a time. so whatever device you are using needs to be up to the specs. I’m using an rpi 3b+ and have no issues.
typically the fan cooling the heatbreak and extruder stays on even with the “extruder” aka part cooler fan turned off