Right. And if you ran MS Works 2.0 for DOS on an XT,
which was 
unfortunately
  what had to be done for a while with me, it would show
characters maybe a
 second after they are type, especially on a Leading Edge Model D, which 
was
  first priority to replace among the 8 XTs that were
slowly being phased 
out.
I've used MSW on XT's (even a PC), and I don't remember its being all that
slow. What were you doing? Editing War & Peace?
  MS-DOS edit or Windows Write works very much faster.
(Don't get me wrong 
here,
  I love the Leading Edge Model D, it's just so damn
slow) 
I think they're pretty quick (faster than the IBM XT, anyway!)