I want to run Linux from a USB stick without affecting the data on the computer.
I need persistence, but I can achieve that through either a Live USB stick, or a full USB installation.
Other than that, my top priority is speed. I believe that with the Live USB stick, all of Linux is loaded into RAM and so it runs quite quickly. I am not sure whether this also applies (or can easily be made to apply) to a full installation.
Having more space and being able to upgrade would also be nice, but are not as important to me as running quickly.
Given the above terms, would it be better for me to use a Live USB or to install Ubuntu fully (possibly with some custom settings to force it to load into RAM)?