Install xfce4-taskmanager by entering the following commands in the terminal:
sudo apt update sudo apt install xfce4-taskmanager
Description:
process manager for the Xfce4 Desktop Environment
A GUI application for monitoring and controlling running processes written for Xfce. It's features include: . *Support for Linux, OpenBSD, FreeBSD and OpenSolaris. *Monitors the CPU and memory usage. *Tree view columns can be reordered. *Display window icons/names. *Customizable with some settings.
Homepage: http://goodies.xfce.org/projects/applications/xfce4-taskmanager
Version: 1.2.0-0ubuntu1
Section: universe/x11