So it makes no difference what you plug in to USB, your MacBook just slows way down (and you probably see the cursor change to a spinning wheel?)
What does your Activity Monitor show? You should notice that a process takes off, maybe several processes.
If you have the listing sorted by CPU use, or in memory tab, by memory use, you should see pretty quickly which processes become active.
This will work best if you launch Activity Monitor first, before you plug anything into a USB port.
(Important questions here!)
1. How much memory (RAM) is installed in your MacBook?
2. How much free space is available on the hard drive?