Fastest? Like I'd realize the speed difference between xterm, urxvt or even Gnome Terminal.
Trust me, when you have really crappy hardware (Intel Atom 1.3GHz w/ 512MB mem), you will notice the difference. Execution of commands that takes 2-3 seconds on Gnome Terminal will be nearly instant on xterm.
Is rxvt slower? Recently I switched from xterm to rxvt-unicode and it's really great!
Not sure... I'll have to give it a go to see if it really is.
Xterm will do 256-colors too. It's the setup I use.
Also, Terminology. Faster than xterm or rxvt.
Uh, I use xterm...
It's obsolete, I know, but it's still the fastest.