RE: redisplay-dont-pause is not mentioned in the Emacs manual

[Drew Adams]

        Kim> Normal redisplay is restarted whenever it is interrupted by user
        input.  For example, pressing and holding the down-arrow key will be
        "randomly jumpy" -- depending on the speed of the computer
      vs. the key "repeat rate" of the keyboard.

    Emacs defers redisplay to input to make sure it does not fall behind.

        Kim> The only way to get "more fluent" display updates is by setting
        redisplay-dont-pause.

    I can't imagine what you mean by "more fluent" display updates, but if
    you observe that the keyboard key repeat mechanism is causing
    redisplay to be pre-empted, it means that keys are coming faster than
    Emacs can redisplay them.  If Emacs does not pre-empt redisplay in
    such a case, it WILL fall behind.  And when you take your finger off
    the key, you will have to wait some length of time for Emacs to finish
    executing and redisplaying the keys that were buffered.

    The value of redisplay pre-emption is precisely for cases like this.

FYI - You replied to me, but the quoted text is from Kim.

FWIW, I think I'm getting more confused now, not less. I thought I
understood better after Kim's message, but now I'm not so sure...

BTW, I think Kim was referring to cursor movement (holding down an arrow
key, for instance), not necessarily to insertion of characters in a buffer.
I guess the idea is the same, however: the display needs to be updated to
show the new cursor location.