No matter the number of cores and RAM on your machine, there comes a time when you begin to question the vitality of your system. However, a quick look at the system monitor will usually allay most of your fears. Desktop distros typically ship with a graphical system monitoring utility, and there are many others on offer through software repos.
Written in Python and released under the LGPL licence, Glances outshines most of its peers with the sheer amount of data it can display. For instance, Glances will display information on combined CPU usage, for machines with a number of cores, but can also show stats for each CPU. The Glances interface features a sidebar on the left that can show TCP connections, disk I/O, filesystem stats and so on, and you can also get the tool to show truncated process names, and even sort processes based on memory/ CPU usage, time, I/O rate and more.