Does anyone have an explanation for why my 'kernel_task' process in MacOS increases intensely after a Simulink simulation?

After simulating a model in Simulink and plotting the results in a 'contourf' plot within a script, my laptop tends to show a high intensity of 'kernel_task' in my Activity Monitor. As a result, my laptop runs hot, as the 'kernel_task' process shows up to 200% of CPU usage. Does anyone have an explanation for this? The simulation within Matlab has already finished when this occurs. Maybe other people running into the same problem?

I use 2018b on MacBook Pro 15 inch 2018.