I’ve been using btop for monitoring system usage and statistics on Linux and MacOS. It’s much better than the built in resource monitors and seems to incur less overhead as well. Being able to use the command line to get insights into what processes are taking up resources is very handy.
It works great on Ubuntu right out of the box (or, more accurately, sudo apt install btop). It also works on MacOS with brew install btop but the colors don’t work quite right on my system unless I set it to the TTY theme. If you don’t like the default options, give it btop a try.