Slow performance when copying files to and from USB devices

When I copy files to and from USB devices (camera, HDD, memory card) my system becomes very slow. For example if I want to close a window I move the mouse but it takes about 2 seconds or more before the mouse cursor moves. When I finally get the cursor over the x and click it nothing happens for 10+ seconds. I’ve tried this with all desktop effects disabled but the issue persists.

What is the command-line equivalent to ‘mintupdate’ for Linux Mint?

Linux Mint has a nice GUI-based Update Manager with selectable update tiers. The defaults are for levels 1 through 3 our of a possible 5 levels. However, I often handle administrative tasks for a number of Linux Mint desktop systems using SSH rather than visiting the physical machines. How do I achieve the same functionality from the command line?