XMeters provides configurable system statistics including CPU, network, memory, and more right in your system tray.
While it does say that it is for the tray, it is optional. On the first run, you are given that option.
Available to monitor are your CPU, storage, network, and memory. You can view it as a bar, pie, or just text. Refresh rates can be adjusted from 3-10 seconds however under 3 seconds requires purchase. Higher settings would see more relevant here however on average it uses 26B of memory. Other settings include showing of individual cores and separate user/privileged utilization. Finally, online updates and online help are built into the app.
XMeters is ideal for anyone wanting to monitor many system functions. It does hold back a few things that you may or may not need but at $4.99, it's worth it should you find it useful.