I was about to buy a 3rd different USB wireless adapter and even considering a PCIe model with external antenna since I kept getting horrible performance with the nano adapters. I liked that they could just be plugged into the back of the system to add wireless support and they worked great on the Raspberry Pi, but on a desktop the performance was not much better than a dial-up connection. Before ordering anther product someone mentioned interference and I then did a bit more digging and found Intel actually published a whitepaper on this subject (Linked at bottom).
After testing I was able to clearly see the effects of 2.4Ghz interference and would recommend to anyone having performance problems with wireless adapters to get a USB extension cable. Using the same Plugable nano-N wireless adapter I ran a speed test from 3 locations:
Connected directly to back USB port
Connected directly to front USB Port
Connected to USB port via extension cable 3′ away
Intel’s Article: http://www.intel.com/content/www/us/en/io/universal-serial-bus/usb3-frequency-interference-paper.html