External install. Use the fastest flash drive you can get. Ok for the browsing & docs or testing but far too slow for anything interesting . External hard drive installs are multiple times faster than on flash drives but these are hampered by the usb transfer rate. - if you had a usb3 caddie and usb3 ports it would almost as good as an internal drive - sata 2.
Saying that, a OLD 5400 speed ide hdd on usb2 works very well, until last Nov thats all I used.