I've been a Linux Mint Cinnamon Guy for several years now (since Linux Mint 13.) I sometimes play in Ubuntu, but Mint is my go-to OS for doing work. As a developer I often have a lot of processes going which sometimes stress my 6GBs of RAM. To keep Mint running at its best I recently added system monitoring to my Cinnamon experience.
First of all I recommend the Multi-Core System Monitor Applet for your taskbar. This applet is the key to staying on top of your system resource status. When you hover over it you get a snapshot of current activity. While you work the CPU and Memory indicators will give you real-time system info.
I should add that you can monitor your file system and network load as well. I'm only interested in CPU and memory on my office desktop, so I deactivated those options in the applet setup. Oh, and you can also change the colors of the indicators, which along with deactivating resource types is a very nice feature.
To get the Multi-Core System Monitor Applet, right-click on the panel.
You'll need to search online applets to find it, but this is what it looks like in the Applet List when you do. If, like me, you install the applet and wonder why it's not displaying in the taskbar panel, be sure to activate it in your Applets control panel!
When you double-click on the applet you'll get excellent reports of what's happening on your system.
Let's not forget about other Linux system monitoring tools like Top. Simply entering “top” at the command line gives you an instance display of applications and processes in real-time.
And of course, if you see something there or in the Applet GUI reports you don't like, you can kill it!
I said it before, I'll say it again. Gotta love Linux!