While the Linux Mint desktop does come with a system monitor, there is another application that you may wish to look at to augment the built-in monitor.
HTop, is a terminal program that allows you to see every single process that is running on your computer, as well as the load on each of your processors.
Head over to the Software Manager and search for htop:
Once installed you will find the program’s launcher in the System Tools menu.
While you can single click each menu element in the interface as shown below. Because it’s running in a terminal window, I find using my arrow keys a lot easier.
There is a nice setup menu so you can customize HTop to your liking.
While it’s running, you can sort processes however you wish, I tend to sort by CPU load so I can find what is causing my system to slow down!
Give HTop a try, it’s a useful tool for your Linux installation.