I was having a cpu overload problem and needed to find out what process was causing the overload. To find that process i used htop. htop is an interactive process viewer, it is a text-mode application for console or X terminals.
To install htop open a terminal window (press Ctrl+Alt+T) and copy+paste the code below in the terminal window.
sudo apt install htop -y
When then installation is finished type: htop to start it.
htop homepage: https://htop.dev/index.html